AI Study

Notes on trustworthy AI and the clinical knowledge that informs my research.

Three parts, in the order they build on each other, and the ontology that ties them together.

Probability & Statistical Inference

Conditioning, Estimation & Decisions
Probability and Bayesian Reasoning
Conditional probability, expectation, independence, and Bayes as the grammar for reasoning about diagnostic evidence.
Probability & Statistical Inference · Conditioning, Estimation & Decisions Read note →
Estimation: Likelihood, Posterior, and What Few Observations Permit
What maximum likelihood actually claims, what a prior adds, and why five observations and five hundred do not license the same statement.
Probability & Statistical Inference · Conditioning, Estimation & Decisions Read note →
Choosing an Estimator: MMSE, MAP, and Maximum Likelihood
Three answers to the same question, what each one optimizes, and which of them needs an integral nobody can evaluate.
Probability & Statistical Inference · Conditioning, Estimation & Decisions Read note →
Bayesian Decision Theory: Risk, Loss, and Where the Boundary Goes
Why the best decision is not always the most probable class, and what a cost matrix does to a threshold.
Probability & Statistical Inference · Conditioning, Estimation & Decisions Read note →
Sampling & Statistical Evidence
The Central Limit Theorem, via Characteristic Functions
Why sums of independent quantities turn Gaussian, shown by the transform that turns convolution into multiplication.
Probability & Statistical Inference · Sampling & Statistical Evidence Read note →
Hypothesis Testing and Sampling Distributions: What a p-Value Can and Cannot Say
The conditional form of every test, why 'at least as extreme' is the operative phrase, and the t and chi-squared distributions that make the calculation possible at all.
Probability & Statistical Inference · Sampling & Statistical Evidence Read note →
Statistical Inference for Diagnostic Studies
Hypothesis testing, confidence intervals, effect size, bootstrap, and multiple comparisons, applied to the claims diagnostic AI papers make.
Probability & Statistical Inference · Sampling & Statistical Evidence Read note →
Latent Variables & Approximate Inference
Information Theory
Entropy, mutual information, and KL divergence as ways to quantify how much a signal carries and how far two distributions have moved.
Probability & Statistical Inference · Latent Variables & Approximate Inference Read note →
Clustering and Mixture Models: k-means, GMM, and the Log of a Sum
Hard assignment by alternating minimization, soft assignment by a density, and the structural reason the mixture likelihood cannot be solved by differentiating.
Probability & Statistical Inference · Latent Variables & Approximate Inference Read note →
Latent Variables: EM and Variational Inference
What to do when neither the parameter nor the variable that produced the data was observed, and why the posterior usually has to be approximated rather than computed.
Probability & Statistical Inference · Latent Variables & Approximate Inference Read note →
Why EM Works: Responsibilities, the Q Function, and the Monotonicity Guarantee
The latent-variable construction of a mixture, the update equations that fall out of it, and the argument that each iteration cannot make the likelihood worse.
Probability & Statistical Inference · Latent Variables & Approximate Inference Read note →
Bayesian Imaging & Model Uncertainty
Bayesian Inverse Problems in Imaging
Denoising and restoration written as inference: an acquisition model as the likelihood, an image prior as the assumption, and what a Markov random field assumes to stay computable.
Probability & Statistical Inference · Bayesian Imaging & Model Uncertainty Read note →
Marginalization, Not Optimization: What Deep Ensembles Are Actually Doing
The frequentist/Bayesian distinction, posterior marginalization, and deep ensembles: deriving predictive uncertainty while separating model averaging from posterior sampling.
Probability & Statistical Inference · Bayesian Imaging & Model Uncertainty Read note →

Linear Algebra & Optimization

Linear Algebra & Geometry
Linear Algebra for Representation Analysis
Eigenvalues, SVD, projection, and PCA as the working tools for asking what a learned representation contains.
Linear Algebra & Optimization · Linear Algebra & Geometry Read note →
Matrix Calculus for Reading Papers: Determinants, Cofactors, and the Gaussian MLE
Matrix differentiation through determinants, cofactors, log determinants and inverses, followed by a complete derivation of Gaussian mean and covariance maximum-likelihood estimators.
Linear Algebra & Optimization · Linear Algebra & Geometry Read note →
Geometry of Representation Spaces
Cosine similarity, manifolds, metric spaces, and what the shape of a latent space says about what a model encodes.
Linear Algebra & Optimization · Linear Algebra & Geometry Read note →
Losses & Gradient Optimization
Choosing the Loss: Squared Error, Absolute Error, and What Each One Believes
Squared error, absolute error and Huber loss: deriving their prediction targets, checking how one bad point affects a fit, and understanding weighted classification losses.
Linear Algebra & Optimization · Losses & Gradient Optimization Read note →
Optimization for Machine Learning
Gradients, regularization, and constrained optimization as the assumptions a training procedure quietly imposes.
Linear Algebra & Optimization · Losses & Gradient Optimization Read note →
Stochastic Gradient Descent and the Optimizers Built On It
Mini-batch gradient estimates, variance, momentum, per-parameter rates in AdaGrad, RMSProp and Adam, and what saddle points and local minima do not explain.
Linear Algebra & Optimization · Losses & Gradient Optimization Read note →
The Exponential Moving Average: One Recursion Behind Momentum, RMSProp and Adam
Deriving the exponential moving average behind momentum, RMSProp and Adam, including bias correction, memory timescales, effective sample size and numerical updates.
Linear Algebra & Optimization · Losses & Gradient Optimization Read note →
Curvature Without the Hessian: Power Iteration, Trace Estimation, and Quantization
Second-order information about a network that is too large to form, estimated by matrix-vector products, and what it is used to decide.
Linear Algebra & Optimization · Losses & Gradient Optimization Read note →
Constraints & Duality
Primal and Dual Problems: The Max-Min Inequality and What the Gap Certifies
The one inequality the whole of Lagrangian duality rests on, why swapping to the dual changes the size of the problem, and why a duality gap is useful information rather than a failure.
Linear Algebra & Optimization · Constraints & Duality Read note →
KKT Conditions and Shadow Prices: What a Lagrange Multiplier Is Actually Telling You
Complementary slackness, the multiplier as the sensitivity of the optimum to its constraint, and reading the SVM's alphas as a statement about which samples matter.
Linear Algebra & Optimization · Constraints & Duality Read note →

Signals, Systems & Transforms

Representations & System Response
Why Complex Exponentials: Choosing the Representation Is Most of the Work
The convolution integral that takes a page, the eigenfunction that takes one line, and what it costs to throw away the transient.
Signals, Systems & Transforms · Representations & System Response Read note →
The Transfer Function Is a Gain, Not a Spectrum
Why H(s) sits in a different category from X(s) and Y(s), what the two numbers in H(jω) actually do to a sine, and why every pole must live in the left half-plane.
Signals, Systems & Transforms · Representations & System Response Read note →
Poles and Zeros: What Comes Out Uninvited, and What Goes In and Vanishes
Why exponentials are the natural test input for a linear system, the physical reading of a pole and a zero, and how a plot of two sets of points summarizes a whole system.
Signals, Systems & Transforms · Representations & System Response Read note →
Fourier Computation & Filter Design
Convolution via the DFT: Circular, Linear, and the Padding You Forgot Was a Choice
Why multiplying two DFTs gives the wrong answer, the length condition that fixes it, and why full/same/valid is the same decision a CNN makes at every layer.
Signals, Systems & Transforms · Fourier Computation & Filter Design Read note →
The FFT: Where a 200× Speedup Comes From
Splitting a transform into its even and odd samples, the recursion that turns N² into N log N, and why an algorithm can matter more than the hardware.
Signals, Systems & Transforms · Fourier Computation & Filter Design Read note →
All-Pass Systems and Group Delay: Distortion That Every Magnitude Test Passes
A system that leaves every frequency's amplitude untouched and still scrambles the signal, and why the magnitude spectrum is exactly the wrong place to look for it.
Signals, Systems & Transforms · Fourier Computation & Filter Design Read note →
FIR Filter Design: When the Optimal Answer Is Optimal for the Wrong Norm
Why truncating the ideal filter is provably best in the L2 sense and still not what you want, what linear phase costs, and the symmetry constraints that forbid whole filter types outright.
Signals, Systems & Transforms · Fourier Computation & Filter Design Read note →
Sampling, Interpolation & Estimation
Resampling and Anti-Aliasing: Why Half of a Checkerboard Is Grey
How downsampling folds the spectrum, why anti-aliasing must come first, and how interpolation, rational resampling, and checkerboard resizing set the filter cutoff.
Signals, Systems & Transforms · Sampling, Interpolation & Estimation Read note →
Fractional Delay: Half a Sample Is Not Half of Two Samples
What it means to shift a discrete signal by a non-integer amount, why the answer is spread over all time, and why the intuitive picture is the one that is wrong.
Signals, Systems & Transforms · Sampling, Interpolation & Estimation Read note →
Linear MMSE Estimation and the Wiener Filter
The best linear estimate of one quantity from another, and why it needs only means and covariances rather than a distribution.
Signals, Systems & Transforms · Sampling, Interpolation & Estimation Read note →
Graph Signals & Spectral Methods
The Graph Laplacian: There Is More Than One, and Choosing Is the Modelling
What the heat equation, spectral clustering and graph networks share in the word Laplacian, why the smallest eigenvectors are the balanced states, and why writing D minus A reflexively skips a decision.
Signals, Systems & Transforms · Graph Signals & Spectral Methods Read note →
Spectral Filtering: Why the Fourier Transform Is a Special Case
The analyze-scale-reconstruct template behind the word spectral, the fact that the Fourier basis is the eigenbasis of a ring graph's Laplacian, and what that licenses for graphs with no coordinates.
Signals, Systems & Transforms · Graph Signals & Spectral Methods Read note →
Graph Neural Networks: Message Passing, Aggregation, and Inductive Node Embeddings
Learning a fixed-length descriptor for every node by repeatedly aggregating its neighbours, why a lookup table cannot embed a node it has never seen, and what makes the parameters independent of graph size.
Signals, Systems & Transforms · Graph Signals & Spectral Methods Read note →

Learning Models & Representation

Learning & Representation Foundations
Perception as Inference: Illusions Are Not Failures, and the Easy Problems Were the Hard Ones
Perception as Bayesian inference: retinal-image ambiguity, illumination and reflectance, Gaussian cue integration, decision costs, active sensing, and Moravec's paradox.
Learning Models & Representation · Learning & Representation Foundations Read note →
Backpropagation, in Scalars and in Matrices
How backpropagation organizes the chain rule to compute derivatives for training, with scalar and matrix derivations for a dense layer and a convolution.
Learning Models & Representation · Learning & Representation Foundations Read note →
Optimizing the Input: Visualization, Style, and Adversarial Examples
What happens when the weights are frozen and the image becomes the free variable, and why the same procedure produces both a picture of a concept and a picture that fools the model.
Learning Models & Representation · Learning & Representation Foundations Read note →
Self-Supervised and Weakly Supervised Learning
Learning from medical data whose labels are scarce, noisy, or only available at the study level.
Learning Models & Representation · Learning & Representation Foundations Read note →
Margins, Kernels & Embeddings
Support Vector Machines: Margin as an Inductive Bias, and What Infeasibility Tells You
Deriving the hard-margin problem from a stability argument, watching it become infeasible when the classes overlap, and reading the soft-margin fix as a priced assumption rather than a repair.
Learning Models & Representation · Margins, Kernels & Embeddings Read note →
The Kernel Trick: Similarity Instead of Coordinates
Why the SVM dual admits a kernel at all, what a kernel is being asked to encode, and how one-class SVM and SVDD turn the same machinery into novelty detection.
Learning Models & Representation · Margins, Kernels & Embeddings Read note →
Recommender Systems: Embeddings, Interactions, and a Field That Audited Itself
Deriving recommendation from sparse categorical features through embeddings, matrix factorization, feature interactions, ranking losses, retrieval metrics, and reproducible evaluation.
Learning Models & Representation · Margins, Kernels & Embeddings Read note →
Sequence Models & Attention
Recurrent Networks and Gating
State carried across time, why gradients through it vanish or explode, and what a gate is actually doing about it.
Learning Models & Representation · Sequence Models & Attention Read note →
Attention: Retrieval as a Differentiable Operation
Deriving query-key-value attention, softmax, square-root dimension scaling, multi-head computation, positional encoding, causal masks, and Transformer costs through explicit examples.
Learning Models & Representation · Sequence Models & Attention Read note →
Speech Recognition: Learning Without Knowing Where Anything Starts
MFCC features, CTC alignment marginalization and forward–backward gradients, with exact frame-to-label path counts, repeated-label constraints and worked decoding examples.
Learning Models & Representation · Sequence Models & Attention Read note →
Spatial Models & Visual Prediction
Fully Convolutional Networks, and Why Detection Needed Its Own Metric
Deriving fully convolutional networks from fully-connected layers, then computing IoU, detection matching, precision-recall, AP, and mAP under explicit evaluation conventions.
Learning Models & Representation · Spatial Models & Visual Prediction Read note →
Anchor Boxes and Non-Maximum Suppression: Where the Priors Are Hidden
Deriving anchor-box geometry, normalized box regression, IoU matching, and non-maximum suppression, with worked examples of reference boxes, losses, and overlapping detections.
Learning Models & Representation · Spatial Models & Visual Prediction Read note →
Invariance and Equivariance: Two Jobs One Network Cannot Do at Once
Deriving translation invariance and equivariance, including convolution, pooling, stride, boundaries, R-FCN position-sensitive pooling, and feature pyramids for detection.
Learning Models & Representation · Spatial Models & Visual Prediction Read note →
Segmentation: Resolution Against Context, and the Things/Stuff Divide
Semantic, instance, and panoptic segmentation derived through pixel losses, receptive fields, encoder-decoder reconstruction, atrous convolution, center offsets, and panoptic quality.
Learning Models & Representation · Spatial Models & Visual Prediction Read note →
Neural Radiance Fields: A Scene Stored as a Function
Deriving NeRF camera rays, volume density, transmittance, alpha compositing, rendering gradients, positional encoding, and the storage-computation tradeoff against voxel grids.
Learning Models & Representation · Spatial Models & Visual Prediction Read note →

Feedback Control & Classical Design

Feedback & Local System Models
Feedback Control: Open Loop, Feedforward, and Why More Feedback Can Be Worse
The three ways to make a system do what you want, the shower that scalds you because the thermostat is by the door, and what that says about a model retraining on data its own deployment produced.
Feedback Control & Classical Design · Feedback & Local System Models Read note →
Linearization: An Approximation Whose Licence Is Retrospective
Pendulum linearization, small-angle sine approximations, Taylor error bounds, phase drift, and the poles that distinguish hanging, inverted, and cart-pole dynamics.
Feedback Control & Classical Design · Feedback & Local System Models Read note →
Transient Response & Stability
Second-Order Systems: Four Numbers You Can Ask For, and Where They Put the Poles
Rise time, overshoot, peak time and settling time are not four independent wishes: each one carves a region out of the complex plane, and the design is whatever survives the intersection.
Feedback Control & Classical Design · Transient Response & Stability Read note →
Routh–Hurwitz: Deciding Stability Without Finding a Single Root
A table of divisions answers a question about polynomial roots that has no formula past degree four, and turns 'is this stable?' into 'for which gains is this stable?'
Feedback Control & Classical Design · Transient Response & Stability Read note →
Performance Limits & Controller Design
What Feedback Buys You, and the One Thing It Cannot
Closing the loop divides plant error and disturbance by the loop gain, and drives steady-state error to zero, but S + T = 1 means sensor noise and reference tracking trade off exactly, at every frequency, forever.
Feedback Control & Classical Design · Performance Limits & Controller Design Read note →
Root Locus and Stability Margins: Two Pictures of the Same Boundary
Watching the closed-loop poles move as a gain sweeps, and reading how much gain and phase you have left off a plot of the open loop: two methods that meet exactly at the edge of stability.
Feedback Control & Classical Design · Performance Limits & Controller Design Read note →

Hepatobiliary Medicine & Imaging

Anatomy & Imaging Foundations
Ultrasound Anatomy of the Liver and Biliary System
The anatomy a sonographer works through, including the variants that change what a normal study looks like.
Hepatobiliary Medicine & Imaging · Anatomy & Imaging Foundations Read note →
Abdominal Ultrasound Physics and Image Formation
Impedance, attenuation, gain, frequency and depth, harmonics, and the artifacts these physics produce.
Hepatobiliary Medicine & Imaging · Anatomy & Imaging Foundations Read note →
Gallbladder Examination and Normal Findings
The scanning protocol, what normal looks like, and the sonographic feature vocabulary: echogenicity, margin, wall, posterior acoustics, Doppler.
Hepatobiliary Medicine & Imaging · Anatomy & Imaging Foundations Read note →
Ultrasound Acquisition Variability and Image Quality
Operator, machine, and preset variation as the dominant nuisance factor, and what it does to a learned model.
Hepatobiliary Medicine & Imaging · Anatomy & Imaging Foundations Read note →
Gallbladder Disease
Gallstones and Cholecystitis
Cholelithiasis, acute and chronic cholecystitis, and the findings that separate them.
Hepatobiliary Medicine & Imaging · Gallbladder Disease Read note →
Adenomyomatosis and Gallbladder Wall Thickening
The benign causes of a thick gallbladder wall, the comet-tail artifact, and the differential it opens.
Hepatobiliary Medicine & Imaging · Gallbladder Disease Read note →
Gallbladder Polyps and Their Malignant Potential
Cholesterol versus adenomatous polyps, the size thresholds that drive management, and why the distinction is hard on ultrasound.
Hepatobiliary Medicine & Imaging · Gallbladder Disease Read note →
Gallbladder Cancer
Features that raise concern for malignancy, the risk factors that shift pretest probability, and where imaging alone cannot settle it.
Hepatobiliary Medicine & Imaging · Gallbladder Disease Read note →
Biliary Disease
Biliary Obstruction
Duct dilatation, the level and cause of obstruction, and what the clinical picture adds.
Hepatobiliary Medicine & Imaging · Biliary Disease Read note →
Choledocholithiasis and Cholangitis
Stones in the common bile duct, and the presentation that turns an imaging finding into an emergency.
Hepatobiliary Medicine & Imaging · Biliary Disease Read note →
Cholangiocarcinoma and Biliary Strictures
Distinguishing benign from malignant strictures, and what each modality can contribute.
Hepatobiliary Medicine & Imaging · Biliary Disease Read note →
Liver Lesions & Multimodal Correlation
Liver Cancer
Hepatocellular carcinoma and hepatic metastasis: surveillance, imaging diagnosis, and the reporting systems used.
Hepatobiliary Medicine & Imaging · Liver Lesions & Multimodal Correlation Read note →
Imaging Across Modalities and Radiology-Pathology Correlation
When ultrasound leads to CT, MRI, or MRCP, and how imaging appearances map back to pathology.
Hepatobiliary Medicine & Imaging · Liver Lesions & Multimodal Correlation Read note →

Evaluation, Generalization & Reliability

Task Definition & Ground Truth
From Clinical Problem to Machine Learning Task
The translation step where most medical AI projects are decided, long before a model is trained.
Evaluation, Generalization & Reliability · Task Definition & Ground Truth Read note →
The Proxy Objective: Training on One Thing, Being Judged on Another
Cross-entropy is not what anyone wants. The metric that matters is usually non-differentiable, unaffordable, or lives in a person's head, so we optimize a stand-in and hope. The gap is structural, not sloppiness.
Evaluation, Generalization & Reliability · Task Definition & Ground Truth Read note →
Dataset Design, Ground Truth, and Reference Standards
What counts as truth in a medical dataset, and how that choice bounds every result that follows.
Evaluation, Generalization & Reliability · Task Definition & Ground Truth Read note →
Label Quality and Interobserver Variability
Evaluating against labels that expert readers themselves disagree about.
Evaluation, Generalization & Reliability · Task Definition & Ground Truth Read note →
When Models Outgrow Their Labels
ImageNet's original labels score about 81% against a careful re-annotation, and several models beat them. Once the ceiling is the annotation rather than the method, the benchmark stops measuring what it reports.
Evaluation, Generalization & Reliability · Task Definition & Ground Truth Read note →
Validation Design & Performance Measures
Data Leakage and Validation Design
How information crosses from test to train in medical data, and what each validation design can claim.
Evaluation, Generalization & Reliability · Validation Design & Performance Measures Read note →
Evaluation Beyond AUROC
Sensitivity and specificity at the operating point that matters, decision curves, and clinical utility.
Evaluation, Generalization & Reliability · Validation Design & Performance Measures Read note →
Matthews Correlation Coefficient: A Metric That Fails Loudly
Why accuracy moves with prevalence and F1 ignores a whole cell of the confusion matrix, and how MCC falls out of a chi-squared test of independence between prediction and truth.
Evaluation, Generalization & Reliability · Validation Design & Performance Measures Read note →
Statistical Evaluation of Diagnostic Models
Confidence intervals, bootstrapping, power, and the pitfalls that recur in diagnostic accuracy papers.
Evaluation, Generalization & Reliability · Validation Design & Performance Measures Read note →
Calibration & Generalization
Calibration, Uncertainty, and Selective Prediction
Whether a stated probability means what it says, and when a model should abstain.
Evaluation, Generalization & Reliability · Calibration & Generalization Read note →
Distribution Shift and Out-of-Distribution Generalization
What breaks when the hospital, scanner, operator, or population changes, and which failures are foreseeable.
Evaluation, Generalization & Reliability · Calibration & Generalization Read note →
Robustness, Subgroup Performance, and External Validation
Robustness to acquisition variability, subgroup analysis, and multi-center validation as tests of generalizability.
Evaluation, Generalization & Reliability · Calibration & Generalization Read note →
Failure Analysis & Clinical Translation
Error and Clinical Failure Analysis
Reading the cases a model gets wrong as evidence about what it learned.
Evaluation, Generalization & Reliability · Failure Analysis & Clinical Translation Read note →
Clinical Validity and Clinical Utility
The difference between a model that measures something real and a model that changes a decision.
Evaluation, Generalization & Reliability · Failure Analysis & Clinical Translation Read note →
Reproducibility, Benchmarks, and Translational Study Design
Designing studies whose results survive contact with another site and another team.
Evaluation, Generalization & Reliability · Failure Analysis & Clinical Translation Read note →

Medical AI Systems & Deployment

Foundation & Multimodal Models
Foundation Models for Medical Imaging
What large pretrained imaging models change about medical AI, and what they do not change about validation.
Medical AI Systems & Deployment · Foundation & Multimodal Models Read note →
Vision-Language and Multimodal Medical AI
Image-text alignment, report grounding, and the failure modes of models that read images and language together.
Medical AI Systems & Deployment · Foundation & Multimodal Models Read note →
Adaptation Across Sites & Time
Domain Adaptation, Domain Generalization, and Test-Time Adaptation
Three answers to the same problem of a model meeting data it was not trained on, and what each assumes.
Medical AI Systems & Deployment · Adaptation Across Sites & Time Read note →
Federated and Continual Learning in Healthcare
Training across institutions that cannot share data, and updating a model without losing what it knew.
Medical AI Systems & Deployment · Adaptation Across Sites & Time Read note →
Generative Systems, Agents & Deployment
Auditing and Evaluating Generative Medical AI
What evaluation means when the output is text or an image rather than a label.
Medical AI Systems & Deployment · Generative Systems, Agents & Deployment Read note →
Medical AI Agents and Tool-Using Clinical Systems
Observe, reason, act: the loop underneath agent systems, and the verification and recovery problems it creates.
Medical AI Systems & Deployment · Generative Systems, Agents & Deployment Read note →
Deployment, Monitoring, and Human-AI Collaboration
Drift after deployment, safety monitoring, automation bias, and what changes with a clinician in the loop.
Medical AI Systems & Deployment · Generative Systems, Agents & Deployment Read note →

Gallbladder AI: Applied Research

Task Definition & Clinical Supervision
Clinical Workflow and Task Definition for Gallbladder AI
Deciding which decision a model supports, and letting that decide the label, the metric, and the design.
Gallbladder AI: Applied Research · Task Definition & Clinical Supervision Read note →
Clinical Feature Annotation and Multi-Task Learning
Building supervision from structured sonographic findings rather than the diagnosis alone.
Gallbladder AI: Applied Research · Task Definition & Clinical Supervision Read note →
Clinical Knowledge-Guided Representation Learning
Using echogenicity, texture, margin, wall features, and anatomical context as domain priors.
Gallbladder AI: Applied Research · Task Definition & Clinical Supervision Read note →
Shortcuts & Confounding
Shortcut Learning and Confounding in Gallbladder Ultrasound
The confounders specific to this problem, and telling a sonographic finding from an acquisition correlate.
Gallbladder AI: Applied Research · Shortcuts & Confounding Read note →
Diagnostic Markers as Shortcut Cues
Calipers, annotations, and machine overlays as predictive artifacts, and what removing them changes.
Gallbladder AI: Applied Research · Shortcuts & Confounding Read note →
Faithfulness & External Validation
Auditing Explanation Faithfulness in Gallbladder Models
How the evidence a diagnostic model exposes can be checked against clinical information assessed separately from it.
Gallbladder AI: Applied Research · Faithfulness & External Validation Read note →
External Validation and Clinical Utility for Gallbladder AI
What it would take for a gallbladder model to be believed at a second hospital, and what its errors would cost.
Gallbladder AI: Applied Research · Faithfulness & External Validation Read note →
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knowledge graph
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Concepts by type around the ring, and every edge an assertion about what holds between them. Hover an edge to read the claim. The corpus graph shows instead which writing discusses which concept.

Ontology

The knowledge graph records which of these notes discusses which concept. This is a different thing: what kind of entity each concept is, and what I hold to be true between them. Every line below is an assertion, so every line is disputable, and the ones resting on published work carry the source. 195 assertions over 101 concepts, in 13 relations.

EvidenceSource6 Finding6 ClinicalTarget7 Standard2 Method41 ModelFamily1 Metric2 Property15 Threat9 Mechanism6 Principle6

assessesProperty

Method · Metric → Property

Provides a procedure or numerical assessment of the property, without establishing it conclusively.

  • Auditing assessesProperty Faithfulness methodological high confidence E01 A frozen-model explanation audit compares the readout's stated importance against the behaviour it purports to explain. no source asserted
  • Intervention & ablation assessesProperty Faithfulness methodological high confidence E02 Controlled perturbations compare attribution-predicted effects with actual score changes, conditional on the perturbation design. arXiv:1901.09392
  • Evaluation metrics assessesProperty Calibration definitional high confidence E03 Calibration measures quantify the discrepancy between predicted probabilities and observed frequencies in a specified population. arXiv:1706.04599
  • Evaluation metrics assessesProperty Faithfulness definitional high confidence E04 Scope: explanation-specific metrics, which quantify agreement between attributed importance and responses under a defined perturbation distribution. arXiv:1901.09392
  • Auditing assessesProperty Plausibility methodological high confidence E05 Blinded clinical review can assess whether an explanation looks reasonable for the task, separately from computational testing. no source asserted
  • Subgroup & fairness assessesProperty Calibration methodological high confidence E06 Calibration can be assessed within prespecified patient or acquisition groups; this does not establish fairness under every criterion. no source asserted
  • Auditing assessesProperty Calibration methodological high confidence E07 An audit can compare frozen-model probabilities with independently obtained outcomes on a declared evaluation population. no source asserted
  • Exploration & stress testing assessesProperty Robustness methodological high confidence E61 Performance under constructed perturbation is the operational assessment of robustness, bounded by the perturbation family chosen. no source asserted
  • Sensitivity analysis assessesProperty Robustness methodological high confidence E66 Varying one design decision at a time measures how much the reported result depends on it, for the decisions someone chose to vary. no source asserted
  • Hypothesis testing assessesProperty Calibration methodological medium confidence E74 A goodness-of-fit test compares predicted frequencies against observed ones, subject to the test's own independence assumptions. no source asserted
  • Intervention & ablation assessesProperty Translation invariance methodological high confidence E93 Shifting the input and measuring the output is a direct test of invariance against equivariance. Classification and localization can be served by separate heads, one invariant and one equivariant, so the two requirements need not conflict. arXiv:1605.06409
  • Sensitivity analysis assessesProperty Stability margin methodological high confidence E107 Sweeping a parameter and locating where behaviour changes qualitatively measures how far the current operating point sits from that boundary. no source asserted
  • Identifiability analysis assessesProperty Causal identifiability methodological high confidence E114 An identification argument specifies the causal target and checks which assumptions connect it to observations; exchangeability, consistency and positivity are one route for treatment effects, not assumptions verified by predictive accuracy. no source asserted
  • Singular value analysis assessesProperty Measurement identifiability methodological high confidence E120 For the specified linear forward model y = A*x, a nonzero null-space vector v makes x and x+v observationally identical. Full column rank removes that ambiguity in the noiseless model, but does not validate the model itself. no source asserted
  • Singular value analysis assessesProperty Inverse-problem conditioning methodological high confidence E121 Inverting a linear forward model divides each observable singular-direction component by its singular value, so small nonzero values amplify measurement error. Regularization can suppress that amplification by changing the estimator, without recovering discarded information. no source asserted
  • Control stability analysis assessesProperty Stability margin methodological high confidence E130 Given an explicit plant, controller, delay model and perturbation family, pole or frequency-domain analysis can locate a stability boundary. The resulting margin belongs to those dynamics, rather than to a classifier's held-out accuracy. no source asserted
  • Diagnostic reasoning assessesProperty Pretest probability methodological high confidence E136 The probability before an index test depends on presentation, history and the referral pathway. Prevalence among patients selected for surgery is not automatically the relevant starting probability for a consecutive outpatient examination. no source asserted
  • Bayesian decision analysis assessesProperty Clinical utility methodological high confidence E139 Expected losses can compare actions under an explicit probability model and clinically justified consequences. This assesses potential value under assumptions; it does not demonstrate that deploying the recommendation improves care. no source asserted
  • Reference standard adjudication assessesProperty Clinical validity methodological high confidence E148 Checking how labels were established tests whether model outputs are being compared with the intended clinical condition. It includes lesion and time correspondence and whether the reference incorporated the index test, rather than assuming a label name guarantees validity. no source asserted
  • Clinical feature annotation assessesProperty Clinical assessability methodological high confidence E150 Calling a finding absent requires enough coverage, resolution and appropriate views to assess it. Some findings require a sequence or manoeuvre, so an apparently negative still frame may instead be unassessable. no source asserted
  • Clinical feature annotation assessesProperty Clinical evidence reliance methodological high confidence E151 Independent feature labels permit comparisons between model behaviour and the clinical evidence available in each case. Correlation or decodability alone remains insufficient; the assessment needs a design that distinguishes feature availability from actual diagnostic use. no source asserted
  • Intervention & ablation assessesProperty Clinical evidence reliance methodological high confidence E152 A controlled edit can test whether output responds to a nominated clinical finding while preserving competing evidence. The conclusion is conditional on the edit changing that finding without introducing other diagnostic or acquisition changes. no source asserted
  • Comparative workflow evaluation assessesProperty Clinical utility methodological high confidence E156 Comparing care with and without the intended use of the system can assess effects on decisions, outcomes, harms and workload. A causal interpretation requires a design addressing alternative explanations for differences between the care pathways. no source asserted
  • Internal validation assessesProperty Calibration methodological high confidence E162 Predictions on held-out patients can be compared with observed frequencies within the sampled setting, accounting for repeated observations per patient. The assessment remains conditional on that population, label process and prediction horizon. no source asserted
  • External validation assessesProperty Transportability methodological high confidence E164 Evaluating a frozen model and preprocessing pipeline in another specified setting tests performance under that setting's acquisition, case mix and reference process. This directly supports a claim about the evaluated conditions; broader transport requires an additional argument. no source asserted
  • Sensitivity analysis assessesProperty Transportability methodological high confidence E168 Varying specified acquisition conditions, case mix or prevalence can expose which assumptions a transport claim depends on. Such checks support only the perturbations actually represented; they are not a substitute for evidence from every proposed setting. no source asserted

probesThreat

Method → Threat

Can investigate a hypothesis about the threat; nominating a candidate is not confirming a mechanism.

  • Auditing probesThreat Shortcut learning methodological high confidence E08 Shortcut hypotheses are explicit audit targets requiring task-specific investigation, not aggregate accuracy. doi:10.1016/S2589-7500(22)00003-6
  • Intervention & ablation probesThreat Shortcut learning empirical high confidence E09 Controlled changes to suspected non-diagnostic cues reveal predictor sensitivity; shown on COVID-19 radiograph classifiers, not gallbladder models. doi:10.1038/s42256-021-00338-7
  • Counterfactual probesThreat Shortcut learning empirical medium confidence E10 Generative comparisons can expose candidate cues, but coupled edits prevent treating each comparison as an isolated intervention. doi:10.1038/s42256-021-00338-7
  • Causal inference probesThreat Confounding definitional high confidence E11 An explicit causal model identifies candidate confounding paths relative to an estimand; it does not discover unmeasured confounders. doi:10.1214/09-SS057
  • Causal inference probesThreat Spurious correlation methodological high confidence E12 Causal analysis separates an observed association from the intervention claim it might be taken to support. doi:10.1214/09-SS057
  • Subgroup & fairness probesThreat Shortcut learning methodological medium confidence E13 Stratifying by suspected cue availability can reveal shortcut-compatible failures; severity and case-mix remain alternative explanations. no source asserted
  • Attribution & saliency probesThreat Shortcut learning empirical medium confidence E14 Attributions nominate suspicious regions for controlled testing; they do not independently establish reliance. doi:10.1038/s42256-021-00338-7
  • Exploration & stress testing probesThreat Shortcut learning methodological high confidence E59 Deliberately constructed conditions can surface a reliance a fixed suite never sampled; absence of a failure under testing is not absence of the reliance. arXiv:2004.07780
  • Exploration & stress testing probesThreat Distribution shift methodological high confidence E60 Perturbation and stress conditions stand in for shifts that have not yet occurred, and only for the shifts someone thought to construct. no source asserted
  • Sensitivity analysis probesThreat Distribution shift methodological high confidence E67 Leave-one-site-out and cohort re-weighting rehearse a shift using variation already present in the assembled data, and reach no further than that variation. no source asserted
  • Out-of-distribution detection probesThreat Distribution shift methodological high confidence E69 A support or density estimate can flag inputs unlike the training set, for the notion of likeness the model was given. doi:10.1162/089976601750264965
  • Sensitivity analysis probesThreat Deployment feedback loop methodological medium confidence E82 Comparing a prospectively recruited stream against operational data can expose divergence the operational data alone cannot show. no source asserted
  • Ensembling probesThreat Distribution shift methodological medium confidence E99 Members that converged to different modes tend to agree where the data constrained the function and diverge where they did not. The signal is informative but neither guaranteed nor specific to distribution shift. arXiv:2002.08791
  • Feedback correction probesThreat Distribution shift methodological high confidence E111 Measuring realized outcomes and correcting against them surfaces divergence between deployment and development conditions that an open pipeline never observes. no source asserted

canIntroduce

Method · Threat · EvidenceSource → Threat

Can create or enable the object. Neither inevitability nor sufficient causation is implied.

  • Confounding canIntroduce Spurious correlation definitional high confidence E15 A common-cause pathway produces association that does not represent the causal effect being estimated. doi:10.1214/09-SS057
  • Spurious correlation canIntroduce Shortcut learning empirical high confidence E16 An association available in training can support a rule that fails when it changes; learning that rule is not inevitable. arXiv:2004.07780
  • Representation learning canIntroduce Shortcut learning empirical high confidence E17 Learned representations can privilege easy predictive cues over the evidence the task intends. arXiv:2004.07780
  • Ultrasound acquisition canIntroduce Spurious correlation empirical high confidence E18 Acquisition and documentation workflows can couple annotations with the target imaged; demonstrated on fetal-ultrasound calipers. doi:10.1007/978-3-031-72111-3_59
  • Intervention & ablation canIntroduce Distribution shift empirical high confidence E19 Removing or replacing regions at test time creates inputs unlike training data; ROAR answers this by retraining, which changes the question. arXiv:1806.10758
  • Screening programs canIntroduce Distribution shift methodological high confidence E20 Moving a model from referred symptomatic patients into screening changes eligibility, prevalence and disease spectrum. no source asserted
  • Deployment & drift canIntroduce Distribution shift empirical high confidence E21 Moving between institutions changes acquisition and patient distributions, as shown for pneumonia models across hospitals. doi:10.1371/journal.pmed.1002683
  • Similarity & graph construction canIntroduce Spurious correlation methodological high confidence E72 A kernel or affinity matrix asserts which cases count as comparable; if acquisition rather than biology drives that similarity, downstream structure inherits it. no source asserted
  • Preprocessing & resampling canIntroduce Spurious correlation methodological medium confidence E76 Resampling without anti-aliasing can stamp a ratio-dependent texture on an image, and the ratio may follow the acquiring scanner. Whether it appears depends on the signal content and the sampling, so it is a mechanism to rule out rather than a universal artefact. doi:10.1109/CVPR52688.2022.01112
  • Deployment & drift canIntroduce Deployment feedback loop methodological high confidence E79 A model whose outputs influence the care that generates its next training data appears in its own input distribution. arXiv:2002.06673
  • Deployment feedback loop canIntroduce Spurious correlation methodological high confidence E81 Under-flagging a subgroup yields fewer confirmed cases in it, which trains the next model to under-flag it further. arXiv:1706.09847
  • Objective design canIntroduce Proxy objective definitional high confidence E83 Choosing a differentiable stand-in for a non-differentiable evaluation target is what creates the gap; the gap follows from the choice, not from poor execution. no source asserted
  • Proxy objective canIntroduce Shortcut learning methodological high confidence E85 A shortcut is precisely a solution scoring well on the proxy and badly on the target, so proxy optimization is the mechanism that rewards it. no source asserted
  • Objective design canIntroduce Outlier influence definitional high confidence E94 A squared residual grants a point influence proportional to its error, so the most anomalous record outweighs many sound ones. doi:10.1214/aoms/1177703732
  • Pseudo-labelling canIntroduce Label noise methodological high confidence E101 A teacher's outputs become the student's training targets, so the teacher's errors are inherited by construction rather than averaged away. doi:10.1109/CVPR42600.2020.01070
  • Pseudo-labelling canIntroduce Spurious correlation methodological medium confidence E102 Systematic teacher error can propagate or amplify: a subgroup the teacher under-detects can train the student to under-detect it further. Random error does not generally cancel back to the true targets, and amplification is not inevitable either. doi:10.1109/CVPR46437.2021.01139
  • Feedback correction canIntroduce Deployment feedback loop definitional high confidence E112 Correcting on a system's own measured output is by construction a closed loop. Whether it converges or diverges depends on the gain around it, but naming that gain requires an explicit model of the update rule and its delays. no source asserted
  • Histopathology canIntroduce Selection & verification bias methodological high confidence E159 When histological verification is available mainly after surgery, restricting evaluation to verified cases conditions on the clinical decision to operate. The resulting case spectrum may differ from that of patients facing the original diagnostic decision. no source asserted

usesEvidence

Method → EvidenceSource · Finding

Observations from the object enter the subject's assessment or reasoning.

  • Diagnostic reasoning usesEvidence Sonographic features definitional high confidence E22 Observed morphology and acoustic findings feed task-specific reasoning without determining the diagnosis alone. no source asserted
  • Diagnostic reasoning usesEvidence Histopathology methodological high confidence E23 A matched tissue result can be incorporated while retaining specimen, sampling and timing limits. no source asserted
  • Diagnostic reasoning usesEvidence Cross-sectional imaging methodological high confidence E24 CT/MRI observations contribute when they address the unresolved clinical question. no source asserted
  • Auditing usesEvidence Sonographic features methodological high confidence E25 Independently assessed findings can anchor an ultrasound evidence audit; annotations derived from the explanation would be circular. no source asserted
  • Auditing usesEvidence Histopathology methodological high confidence E26 Matched tissue diagnoses support outcome verification but cannot substitute for annotations of image-visible evidence. no source asserted
  • Concept-based methods usesEvidence Sonographic features methodological medium confidence E27 Independently annotated sonographic findings can be operationalized as concepts, given validated measurement and separation. no source asserted
  • Bayesian inference usesEvidence Clinical history & examination methodological high confidence E134 Clinical context supplies information for the prior and likelihood appropriate to the target patient population. Information already included in the prior must not be counted again as independent new evidence in the diagnostic update. no source asserted
  • Bayesian decision analysis usesEvidence Clinical history & examination methodological high confidence E138 History and examination help specify candidate actions, contraindications and their consequences. A disease posterior becomes an action recommendation only after the clinically relevant consequences are assigned losses. no source asserted
  • Reference standard adjudication usesEvidence Histopathology methodological high confidence E145 Tissue findings can anchor a diagnostic label only through an explicit correspondence between specimen, lesion, patient and examination time. The same tissue diagnosis does not make its defining morphology visible in every associated image. no source asserted
  • Reference standard adjudication usesEvidence Longitudinal follow-up methodological high confidence E146 Follow-up can adjudicate later events or disease evolution, but loss of observation before the target horizon is not an automatic negative label. The reference must distinguish censoring, competing events and genuinely observed event-free follow-up. no source asserted
  • Reference standard adjudication usesEvidence Clinical history & examination methodological high confidence E147 Index-time symptoms and examination findings can form part of a clinical target definition. An image-only surrogate cannot silently replace them when the diagnosis depends on clinical context. no source asserted
  • Clinical feature annotation usesEvidence Sonographic features methodological high confidence E149 Independent annotation records which features are present, absent, uncertain or unassessable in the available examination. Blinding to model output and, where appropriate, the final diagnosis helps avoid writing the prediction back into its supposed evidence. no source asserted
  • Clinical feature annotation usesEvidence Electrophysiological features methodological high confidence E187 Annotation can distinguish a waveform event and its time interval from the patient's broader neurological diagnosis. This prevents a patient-level label from being treated as evidence that every sampled window contains a visible event. no source asserted

providesEvidenceFor

EvidenceSource · Finding → ClinicalTarget

Can supply observations bearing on the clinical question, without alone resolving it.

  • Ultrasound acquisition providesEvidenceFor Gallbladder disease empirical high confidence E28 Adequately acquired ultrasound supplies diagnostically relevant gallbladder observations. doi:10.1007/s13244-017-0544-7
  • Sonographic features providesEvidenceFor Gallbladder disease empirical high confidence E29 Findings such as intramural cystic spaces support particular differentials; no generic feature establishes every disease. doi:10.1007/s13244-017-0544-7
  • Sonographic features providesEvidenceFor Malignancy & staging empirical high confidence E30 Scope: malignancy-risk assessment of gallbladder polyps. Morphology and size inform risk, not a pathological stage. doi:10.1007/s00330-021-08384-w
  • Histopathology providesEvidenceFor Malignancy & staging empirical high confidence E31 Appropriately sampled tissue establishes malignant histology and sampled invasion, not necessarily the complete stage. no source asserted
  • Cross-sectional imaging providesEvidenceFor Malignancy & staging empirical high confidence E32 CT/MRI supplies evidence about tumour extent and spread, with limits for microscopic disease. doi:10.1259/bjr.20200726
  • Cross-sectional imaging providesEvidenceFor Biliary tract empirical high confidence E33 Scope: MRCP assessment of ductal configuration, narrowing and filling defects; these do not alone determine cause. no source asserted
  • Ultrasound acquisition providesEvidenceFor Liver & hepatobiliary empirical high confidence E34 Ultrasound supplies observations of parenchyma and the visible hepatobiliary system, subject to acoustic access. no source asserted
  • Cross-sectional imaging providesEvidenceFor Neurological disease empirical high confidence E35 Scope: CT/MRI in stroke assessment, including haemorrhage or ischaemic injury; not every neurological diagnosis. doi:10.3174/ajnr.A3690
  • Histopathology providesEvidenceFor Gallbladder disease empirical high confidence E36 A matched specimen provides tissue-level evidence for the sampled lesion; surgical selection limits generalization. no source asserted
  • Clinical history & examination providesEvidenceFor Cardiovascular risk methodological high confidence E157 Baseline history and current treatment help define the patient and care setting for a risk estimate. Without their timing, observed risk can be confused with the risk before treatment or with treatment benefit. no source asserted
  • Longitudinal follow-up providesEvidenceFor Cardiovascular risk methodological high confidence E158 Risk over a specified horizon concerns future events, so later observations supply evidence that a baseline cross-section cannot provide. Censoring and competing events determine which conclusions those observations support. no source asserted
  • Duct dilatation providesEvidenceFor Biliary tract empirical high confidence E176 The location and extent of enlargement can help localize a biliary problem. They do not by themselves identify the cause, establish active obstruction or determine the presence of infection. no source asserted
  • Wall thickening providesEvidenceFor Gallbladder disease empirical high confidence E177 Thickness and its pattern bear on the differential diagnosis, but inflammation, benign remodelling and malignancy can overlap. Treating this broad finding as a cancer label discards the clinical alternatives. no source asserted
  • Intramural cystic spaces providesEvidenceFor Gallbladder disease empirical high confidence E178 Resolved intramural spaces can support a wall-remodelling explanation in the appropriate pattern. Their absence in a limited image is weaker evidence than their confident absence after an adequate examination. no source asserted
  • Posterior acoustic effects providesEvidenceFor Gallbladder disease empirical high confidence E179 A shadow behind a suspected calculus or comet-tail echoes arising in a wall can change the interpretation of a lesion. An audit that removes all tissue outside the lesion outline may remove precisely this evidence. no source asserted
  • Electrophysiological features providesEvidenceFor Neurological disease empirical high confidence E180 Electrical discharges can bear on an epilepsy assessment, but a discharge, a recorded clinical event and a diagnosis of recurrent seizure predisposition are different targets. A normal short recording does not universally exclude the disease. no source asserted
  • Cross-sectional imaging providesEvidenceFor Acute stroke triage methodological high confidence E192 Brain, vascular and tissue imaging can answer different urgent questions about haemorrhage, arterial occlusion and tissue state. The acquisition protocol determines which question an image can support; success on one task does not establish suitability for the others. no source asserted
  • Clinical history & examination providesEvidenceFor Gallbladder disease methodological high confidence E193 Symptoms and examination findings help distinguish an incidental structural finding from an acute clinical syndrome. An image showing a stone is not by itself a complete reference for diagnosing inflammation or deciding urgency. no source asserted

constrainsProcedure

Standard → Method · Metric

Specifies decision rules or reporting requirements. Compliance is not guaranteed.

  • Clinical guidelines constrainsProcedure Diagnostic reasoning methodological high confidence E37 Applicable guidelines specify how defined findings and risk factors inform a decision; the example is polyp management. doi:10.1007/s00330-021-08384-w
  • Clinical guidelines constrainsProcedure Screening programs methodological high confidence E38 A screening guideline supplies eligibility and follow-up rules against which a workflow can be specified and audited. no source asserted
  • Reporting standards constrainsProcedure Auditing methodological high confidence E39 Scope: diagnostic-accuracy components. STARD specifies reporting of participants, reference procedures and analysis. doi:10.1136/bmj.h5527
  • Reporting standards constrainsProcedure Evaluation metrics methodological high confidence E40 Reporting requires specified estimates and their precision; compliance does not make a metric appropriate for every claim. doi:10.1136/bmj.h5527
  • Reporting standards constrainsProcedure Operating point selection definitional high confidence E89 Reporting a threshold-free summary alone leaves the clinically consequential choice of operating point undocumented. doi:10.1371/journal.pone.0118432

warrantsReassessmentOf

Threat → Property · Method

Gives reason to reassess; does not assert that anything has deteriorated.

  • Distribution shift warrantsReassessmentOf Calibration methodological high confidence E41 Calibration established on one distribution need not persist on another, so reassessment is warranted. arXiv:1906.02530
  • Distribution shift warrantsReassessmentOf Uncertainty & abstention methodological high confidence E42 Shift motivates checking uncertainty quality and the risk and coverage of any acceptance policy. arXiv:1906.02530
  • Distribution shift warrantsReassessmentOf Subgroup & fairness methodological high confidence E43 Changed populations or acquisition conditions require reassessing subgroup performance; aggregate results cannot answer it. no source asserted
  • Distribution shift warrantsReassessmentOf Robustness methodological high confidence E64 A realized shift may or may not fall inside the perturbation family over which robustness was assessed; it warrants checking that coverage rather than establishing that the assessment no longer applies. no source asserted
  • Shortcut learning warrantsReassessmentOf Out-of-distribution detection methodological medium confidence E70 If a site signature is part of what the detector learned to call normal, it can flag a new scanner while passing novel pathology from the familiar one. This is a failure mode to test for, not a guaranteed behaviour. no source asserted
  • Deployment feedback loop warrantsReassessmentOf Calibration methodological high confidence E80 Once the data reflect the model's own influence, agreement between predictions and recorded outcomes still establishes calibration under that policy and observation process, but no longer under an untreated or differently acted-upon population. no source asserted
  • Proxy objective warrantsReassessmentOf Faithfulness definitional high confidence E84 A model optimized toward a stand-in has been selected for scoring well on the stand-in; that its reliance matches the target is a question the training never posed. no source asserted
  • Proxy objective warrantsReassessmentOf Auditing definitional high confidence E86 When the audit's own measure is itself a stand-in for what is being audited, the audit inherits the gap it was meant to detect. no source asserted
  • Proxy objective warrantsReassessmentOf Uncertainty & abstention definitional medium confidence E87 Confidence calibrated against the training objective expresses certainty about the stand-in, which is not certainty about the clinical target. no source asserted
  • Outlier influence warrantsReassessmentOf Robustness definitional high confidence E95 A fit skewed by a few contaminated records reports an ordinary residual and an ordinary summary; nothing in the output marks the disproportion. no source asserted
  • Shortcut learning warrantsReassessmentOf Ensembling methodological high confidence E100 Members sharing an architecture, a training set and a preprocessing pipeline share the biases those impose, so a shortcut present in the data can leave them agreeing confidently and wrong together. Agreement is therefore weak evidence of correctness under a shared shortcut. no source asserted
  • Label noise warrantsReassessmentOf Auditing definitional high confidence E103 When the reference standard is itself several points from correct, disagreement between model and standard no longer separates model error from annotation error. arXiv:2006.07159
  • Label noise warrantsReassessmentOf Calibration definitional high confidence E104 Probabilities fitted to agree with noisy labels are calibrated to the annotation process, and the agreement is evidence about that process rather than about the condition. arXiv:2006.07159
  • Deployment feedback loop warrantsReassessmentOf Stability margin methodological medium confidence E110 A path from a model's outputs back into its own training data is a feedback path, so a margin measured on the open pipeline need not bound the deployed one. The control reading holds only where the dynamics, delays and update rule are made explicit; a learning loop does not automatically possess a defined gain margin. no source asserted
  • Selection & verification bias warrantsReassessmentOf Pretest probability definitional high confidence E160 Prevalence among verified or referred cases need not equal prevalence among consecutive intended-use patients. The selection mechanism must be examined before using that frequency as a clinical prior. no source asserted
  • Selection & verification bias warrantsReassessmentOf Clinical validity definitional high confidence E161 Accuracy conditional on receiving a reference examination is not automatically accuracy in the target population. Differential verification or missing outcomes can change which errors are observable. no source asserted
  • Distribution shift warrantsReassessmentOf Pretest probability definitional high confidence E167 A change in referral or recruitment may alter baseline disease odds. Retaining the development prior requires evidence about the new clinical population, rather than an assumption that all shifts leave prevalence unchanged. no source asserted
  • Deployment feedback loop warrantsReassessmentOf Transportability definitional high confidence E191 If deployment changes who is tested, treated or labelled, the future data-generating process can depend on the policy itself. Validation under the previous care policy does not by itself cover the resulting feedback regime. no source asserted

doesNotEstablish

Property · Method · Metric · EvidenceSource · Standard → Property · Finding

The subject alone is insufficient to establish the object. Non-entailment, not incompatibility.

  • Plausibility doesNotEstablish Faithfulness definitional high confidence E44 A visually convincing explanation can be insensitive to learned parameters, so reasonableness does not entail faithfulness. arXiv:1810.03292
  • Faithfulness doesNotEstablish Plausibility definitional high confidence E45 A faithful explanation of caliper reliance accurately describes an inappropriate rule without making it clinically plausible. no source asserted
  • Calibration doesNotEstablish Faithfulness definitional high confidence E46 Agreement between probabilities and outcome frequencies does not constrain whether an explanation describes the predictor. no source asserted
  • Evaluation metrics doesNotEstablish Faithfulness definitional high confidence E47 Scope: predictive-performance metrics such as AUROC. They describe predictions against labels, not the computation. no source asserted
  • Segmentation & detection doesNotEstablish Faithfulness definitional high confidence E48 Localization or mask overlap does not establish that an explanation identifies the evidence a diagnostic predictor used. no source asserted
  • Histopathology doesNotEstablish Sonographic features definitional high confidence E49 A tissue diagnosis does not establish that a finding was visible or assessable in the frame supplied to the model. no source asserted
  • Reporting standards doesNotEstablish Faithfulness definitional high confidence E50 A compliant report can describe a method whose faithfulness claim remains unsupported. no source asserted
  • Evaluation metrics doesNotEstablish Robustness definitional high confidence E63 A score on a held-out sample from one distribution quantifies performance on that distribution and asserts nothing about behaviour under shift. no source asserted
  • Robustness doesNotEstablish Faithfulness definitional high confidence E65 Stability under perturbation of the learned representation is compatible with that representation encoding a shortcut; a wide margin around the wrong feature is still a wide margin. no source asserted
  • Evaluation metrics doesNotEstablish Plausibility definitional high confidence E68 A performance figure quantifies agreement with labels and carries no claim about whether the model's reasoning would be recognized as sensible. no source asserted
  • Out-of-distribution detection doesNotEstablish Robustness definitional high confidence E71 Declining to answer on inputs judged unfamiliar is not evidence of correct behaviour on inputs judged familiar. no source asserted
  • Hypothesis testing doesNotEstablish Robustness definitional high confidence E75 A p-value is conditional on the null being true and supplies no probability that any hypothesis holds, let alone that performance transports. doi:10.1080/00031305.2016.1154108
  • Translation invariance doesNotEstablish Faithfulness definitional high confidence E92 A representation trained to be unchanged by position has been rewarded for discarding the spatial correspondence that an attribution map asserts. no source asserted
  • Attention mechanism doesNotEstablish Faithfulness definitional high confidence E97 An attention weight reports how much a value vector was routed into an update; by the second layer that vector already summarizes much of the sequence, so the weight is a routing diagram and not an attribution. arXiv:1706.03762
  • Ensembling doesNotEstablish Calibration definitional high confidence E98 Spread across independently initialized models supplies a predictive distribution where a point estimate supplies only a score, but the spread is a property of the ensemble, not a comparison with observed outcomes. Calibration assessment requires that comparison. arXiv:1612.01474
  • Evaluation metrics doesNotEstablish Stability margin definitional high confidence E108 A point estimate on a fixed test set reports current performance; it says nothing about how far inputs or thresholds can move before that performance fails. no source asserted
  • Operating point selection doesNotEstablish Stability margin definitional high confidence E109 Choosing a threshold fixes an operating point without quantifying how much the score distribution may shift before the choice stops holding. no source asserted
  • Causal identifiability doesNotEstablish Clinical utility definitional high confidence E115 Identifying a treatment effect does not establish that a learned decision rule improves care: the policy, patient population, competing consequences and implementation still need assessment. no source asserted
  • Simulation-based policy evaluation doesNotEstablish Clinical utility definitional high confidence E118 A favourable simulated return is conditional on the state, action, reward and transition model. It is not an observed improvement in patient outcomes, and a reward can omit harms that matter clinically. no source asserted
  • Constrained optimization doesNotEstablish Clinical validity definitional high confidence E119 Even a certified global optimum only solves the stated objective over the stated feasible set; it cannot repair a mismatched clinical target, an invalid reference label or a constraint that encodes the wrong requirement. no source asserted
  • Measurement identifiability doesNotEstablish Clinical assessability definitional high confidence E122 A unique solution in a noiseless model can remain too sensitive to noise or finite resolution to support a finding in the actual examination. Uniqueness and usable measurement precision are different requirements. no source asserted
  • Evaluation metrics doesNotEstablish Inverse-problem conditioning definitional high confidence E123 Error on a fixed test set does not report how much a reconstructed quantity can change under measurement perturbations; that requires a forward model, perturbation scale and sensitivity assessment. no source asserted
  • Inverse reconstruction doesNotEstablish Sonographic features definitional high confidence E128 A structure present in a reconstructed image may be supplied by the reconstruction prior rather than resolved by the acquired echoes. Its appearance alone does not establish that the corresponding finding was measured in this patient. no source asserted
  • Stability margin doesNotEstablish Clinical utility definitional high confidence E131 A loop can remain stable while regulating the wrong quantity or pursuing a clinically harmful target. Distance from an instability boundary does not establish benefit from the action being stabilized. no source asserted
  • Bayesian inference doesNotEstablish Calibration definitional high confidence E135 A posterior is conditional on its probability model and prior; those choices can be wrong for the deployment population. Calling an output Bayesian does not replace checking agreement between its probabilities and observed outcomes. no source asserted
  • Faithfulness doesNotEstablish Clinical evidence reliance definitional high confidence E153 An explanation can accurately report that the model used a site marker or another shortcut. Correctly describing the computation does not make its evidence clinically appropriate. no source asserted
  • Clinical validity doesNotEstablish Clinical utility definitional high confidence E154 An output can correspond accurately to the intended clinical condition without improving decisions or patient outcomes. Clinical benefit additionally depends on what users do with it and on the consequences compared with usual care. no source asserted
  • Hypothesis testing doesNotEstablish Clinical validity definitional high confidence E155 Rejecting a statistical null under the sampling model cannot repair a wrong target, a biased reference process or an incorrect unit of analysis. Statistical significance does not turn those observations into evidence for the intended clinical claim. no source asserted
  • Internal validation doesNotEstablish Transportability definitional high confidence E163 An independent split can still share acquisition, referral, treatment and labelling mechanisms with development. Independence of held-out patients does not test whether the model's behaviour persists when those mechanisms change. no source asserted
  • External validation doesNotEstablish Clinical evidence reliance definitional high confidence E165 A shortcut can persist across institutions, so successful external prediction does not identify which evidence the model used. Testing transport and testing clinical reliance answer different questions. no source asserted
  • External validation doesNotEstablish Clinical utility definitional high confidence E166 Retrospective performance on another site's cases does not show how clinicians act on the output or whether outcomes improve. Those consequences require assessment of the intended use within care. no source asserted
  • Clinical validity doesNotEstablish Clinical evidence reliance definitional high confidence E169 Agreement with a valid clinical target can coexist with reliance on a correlated care-process cue. A correct diagnosis and a correct account of which clinical evidence produced it are separate claims. no source asserted
  • Representation learning doesNotEstablish Transportability definitional high confidence E195 A descriptor fitted as a free per-case vector has no rule mapping a new case's observations to a vector, so nothing in the fitted table applies to a case absent at training time. Optimizing an appended row afterwards is additional fitting, not inference through the trained model. no source asserted

canAudit

Method → Method · ModelFamily · EvidenceSource

Instances or outputs of the object can be explicit inspection targets of the subject.

  • Auditing canAudit Foundation models methodological high confidence E51 An adapted instance can be frozen and audited for its evidence use; pretraining scale is not an exemption. no source asserted
  • Auditing canAudit Representation learning methodological high confidence E52 Representations can be inspected for encoded clinical and acquisition information, keeping decodability separate from reliance. no source asserted
  • Auditing canAudit Segmentation & detection methodological high confidence E53 Segmentation outputs can be audited for dependence on documentation cues. doi:10.1007/978-3-031-72111-3_59
  • Auditing canAudit Attribution & saliency methodological high confidence E54 Parameter and label randomization test whether attribution outputs respond to the learned predictor at all. arXiv:1810.03292
  • Auditing canAudit Concept-based methods methodological high confidence E55 Audit the concept examples, held-out measurement quality, correlated concepts and claimed sensitivity. no source asserted
  • Auditing canAudit Counterfactual methodological high confidence E56 Inspect whether an edited comparison changes its intended target while preserving other evidence. no source asserted
  • Exploration & stress testing canAudit Foundation models methodological medium confidence E62 Stress conditions can be applied to a fixed model's outputs without access to its training data. no source asserted
  • Subgroup & fairness canAudit Similarity & graph construction methodological medium confidence E73 Degree normalization decides how far the densely connected majority sets the geometry, so the graph construction is itself a legitimate target of subgroup analysis. no source asserted
  • Auditing canAudit Preprocessing & resampling methodological high confidence E78 The pipeline that produced the inputs is itself an inspection target, and one that attribution over image content cannot reach. no source asserted
  • Operating point selection canAudit Subgroup & fairness methodological high confidence E88 One threshold applied across groups of differing prevalence produces different error profiles per group; sweeping it exposes that dependence. doi:10.1145/3287560.3287598
  • Auditing canAudit Post-processing methodological high confidence E91 The steps between a network's output and the reported result are a separate inspection target; a fault there is invisible to any method examining only the model. no source asserted
  • Auditing canAudit Objective design methodological high confidence E96 Loss choice and per-sample weighting are where class priorities are actually encoded; reading them is more direct than inferring priorities from performance. no source asserted
  • Auditing canAudit Pseudo-labelling methodological high confidence E105 The labelling model is an inspection target in its own right, and one that evaluating the final model against those same labels cannot reach. no source asserted

changesObservabilityOf

EvidenceSource · Method → Finding

Can change the visibility or assessability of findings without a change in underlying disease.

  • Ultrasound acquisition changesObservabilityOf Sonographic features empirical high confidence E57 Acquisition modes alter acoustic findings; spatial compounding changed shadow appearance in a stone phantom. doi:10.1148/rg.2017160175
  • Intervention & ablation changesObservabilityOf Sonographic features methodological high confidence E58 Masking can erase diagnostically relevant morphology as well as the suspected nuisance cue. no source asserted
  • Preprocessing & resampling changesObservabilityOf Sonographic features methodological high confidence E77 Interpolation and filtering can suppress fine texture that a reader or model would otherwise assess. no source asserted
  • Post-processing changesObservabilityOf Sonographic features methodological high confidence E90 Overlap-based suppression deletes true detections lying closer than its threshold, after the model has already scored them. doi:10.1109/TPAMI.2016.2577031
  • Implicit representation changesObservabilityOf Sonographic features methodological medium confidence E106 A field queried between its training views renders interpolated structure with the same appearance as measured structure, and the output carries no marker separating them. doi:10.1007/978-3-030-58452-8_24
  • Ultrasound acquisition changesObservabilityOf Duct dilatation empirical high confidence E181 Duct calibre must be assessed in an adequately visualized segment and plane. Obscuration or incomplete coverage can make a normal-looking frame uninformative about the rest of the biliary tree. no source asserted
  • Ultrasound acquisition changesObservabilityOf Intramural cystic spaces empirical high confidence E182 Depth, focus, resolution and the chosen plane affect whether small intramural spaces can be resolved. A change in their visibility across images need not indicate a change in the wall's underlying structure. no source asserted
  • Ultrasound acquisition changesObservabilityOf Posterior acoustic effects empirical high confidence E183 Beam angle and compounding can change the appearance of shadows and reverberation. Their stability under an image transformation cannot be assumed merely because the biological lesion is unchanged. no source asserted
  • Preprocessing & resampling changesObservabilityOf Intramural cystic spaces methodological high confidence E184 Reducing spatial resolution can remove a small resolved cavity while preserving the overall thickened-wall outline. Preserving the coarse diagnostic label therefore does not guarantee preservation of the evidence used to justify it. no source asserted
  • Electrophysiological recording changesObservabilityOf Electrophysiological features empirical high confidence E186 Electrode placement, montage, filtering and recording duration affect which electrical phenomena can be observed. Failure to capture an intermittent event is a limit of the observation as well as a possible clinical negative. no source asserted

limitsClaim

Principle · Property → Method · Metric · Property

Constrains what can be inferred or jointly guaranteed under the assumptions named in the assertion; does not assert an empirical failure.

  • Identifiability criterion limitsClaim Causal inference definitional high confidence E113 If two causal models satisfy the stated assumptions and generate the same observational distribution but disagree on the target effect, that effect is not identified; more observations from that same distribution cannot resolve the disagreement. no source asserted
  • Identifiability criterion limitsClaim Counterfactual definitional high confidence E116 An identified interventional distribution need not identify an individual counterfactual. Changing pixels tests a computational input intervention; interpreting the result as what would have happened to the patient requires an additional causal argument. no source asserted
  • Identifiability criterion limitsClaim Simulation-based policy evaluation definitional high confidence E117 Dynamics can agree on every observed action yet disagree on actions absent from the records. A simulator chooses among those possibilities through assumptions; agreement with retrospective trajectories alone does not identify the value of an unsupported policy. no source asserted
  • Sampling theorem limitsClaim Measurement identifiability definitional high confidence E124 For a signal band-limited to B, ideal noiseless uniform sampling above 2B permits reconstruction. If the admissible signal class instead contains aliases, distinct continuous signals can produce the same samples and the original is not uniquely determined. no source asserted
  • Sampling theorem limitsClaim Preprocessing & resampling definitional high confidence E125 Before decimation, frequencies outside the new representable band must be removed if aliasing is to be excluded for arbitrary inputs. Upsampling after folding has occurred cannot determine which original frequency produced a sampled component. no source asserted
  • Data processing inequality limitsClaim Representation learning definitional high confidence E126 For a fixed encoder whose only patient-specific input is the image, processing cannot increase mutual information with disease relative to that input. It can make existing information easier for a chosen decoder to use; dependence still does not establish causal relevance. no source asserted
  • Data processing inequality limitsClaim Inverse reconstruction definitional high confidence E127 With a fixed reconstruction model and no additional patient measurements, a prior can select or average among compatible images but cannot add patient-specific information absent from the input. A plausible reconstruction is therefore not a new observation. no source asserted
  • Feedback sensitivity identity limitsClaim Feedback correction definitional high confidence E129 For the scalar negative-feedback loop S = 1/(1+L) and T = L/(1+L), S+T=1 and hence |S|+|T|>=1 wherever defined. Suppressing output-disturbance transmission through S leaves sensor-noise transmission through T near unity; this is not a theorem about arbitrary clinical learning loops. no source asserted
  • Bias-variance decomposition limitsClaim Evaluation metrics definitional high confidence E132 Under squared loss with conditionally zero-mean test noise independent of training, expected prediction error decomposes into squared bias, estimator variance and irreducible noise. A single test score does not identify those terms, and the identity does not impose a conserved budget preventing bias and variance from both improving. no source asserted
  • Bayes error bound limitsClaim Operating point selection definitional high confidence E133 With nonzero class priors and overlapping class-conditional distributions on a set of positive probability, the fixed measurements imply positive Bayes classification error. A threshold cannot make both false positives and false negatives vanish; precision and recall nevertheless have no universal conserved sum, and better measurements can change the bound. no source asserted
  • Pretest probability limitsClaim Predictive values definitional high confidence E137 Bayes' rule gives PPV = Se*pi/(Se*pi + (1-Sp)*(1-pi)) for sensitivity Se, specificity Sp and prevalence pi. Transferring a positive predictive value therefore requires the target prevalence and justification that the conditional test characteristics also transfer. no source asserted
  • Clinical assessability limitsClaim Clinical evidence reliance definitional high confidence E185 When the acquisition cannot resolve a specified finding, agreement with a patient diagnosis cannot establish reliance on that finding in this image. Prediction may instead depend on other measured evidence or on prior information; human difficulty alone is not proof of physical non-observability. no source asserted
  • Data processing inequality limitsClaim Similarity & graph construction definitional high confidence E194 Each message-passing layer is a function of the previous layer's states, so a node descriptor can carry no information about a relation that the edge rule did not already supply. Repeated neighbourhood averaging contracts the differences it does not preserve; adding depth cannot recover them. no source asserted

setsRequirementsFor

ClinicalTarget → Method · Metric

The clinical question determines which target, unit, timing, evidence, or consequence the procedure or metric must address.

  • Gallbladder disease setsRequirementsFor Intended use specification definitional high confidence E140 Detecting a stone, diagnosing acute inflammation and characterizing possible malignancy are different questions. Each requires its own target, unit of analysis, available inputs and intended clinical action before a performance claim has a determinate meaning. no source asserted
  • Malignancy & staging setsRequirementsFor Reference standard adjudication definitional high confidence E141 A specimen-level cancer diagnosis must be matched to the imaged lesion and relevant examination time. Patient-level staging cannot simply become a positive label for every image frame. no source asserted
  • Cardiovascular risk setsRequirementsFor Reference standard adjudication definitional high confidence E142 A prognostic label needs a baseline, prediction horizon and outcome definition, with explicit treatment of censoring and competing events. Outcomes observed under treatment do not directly label the patient's untreated risk. no source asserted
  • Acute stroke triage setsRequirementsFor Evaluation metrics definitional high confidence E143 A triage claim must account for which urgent cases are missed, which alerts consume attention and when a result changes action. Ranking accuracy or isolated inference time does not measure the full clinical delay. no source asserted
  • Neurological disease setsRequirementsFor Clinical feature annotation methodological high confidence E144 A visible movement, an electrical discharge and a longitudinal neurological diagnosis are different annotation targets. The protocol must state the observation interval and relevant clinical state rather than treating an unrecorded phenomenon as absent. no source asserted
  • Gallbladder disease setsRequirementsFor Intervention & ablation methodological high confidence E188 For an audit of stone or wall-lesion evidence, preserving the lesion outline is insufficient if the edit destroys posterior shadowing or intramural detail. Clinical interpretation determines which surrounding signal must remain controlled. no source asserted
  • Acute stroke triage setsRequirementsFor Comparative workflow evaluation definitional high confidence E189 A claim of faster clinically useful triage requires measuring the path from acquisition to review and action, including alert burden and downstream delays. Faster computation alone cannot establish a shorter treatment pathway. no source asserted
  • Cardiovascular risk setsRequirementsFor Bayesian decision analysis definitional high confidence E190 Choosing prevention requires expected benefits and harms of an action, not only the probability of an event under observed care. A risk predictor must not be silently reinterpreted as an estimate of treatment effect. no source asserted

canManifestAs

Mechanism → Finding

Can generate the finding under specified biological or measurement conditions; neither necessary presence nor diagnostic specificity is implied.

  • Biliary obstruction canManifestAs Duct dilatation empirical high confidence E170 Impaired bile outflow can produce upstream duct enlargement, but its visibility depends on timing and context. Dilatation can persist after obstruction is relieved, and a nondilated duct does not universally exclude obstruction. no source asserted
  • Inflammatory change canManifestAs Wall thickening empirical high confidence E171 Inflammation can produce gallbladder wall oedema and thickening. The morphology is not specific to inflammation, so the same measurement needs clinical context and competing explanations. no source asserted
  • Neoplastic invasion canManifestAs Wall thickening empirical high confidence E172 An infiltrating gallbladder malignancy can present as wall thickening rather than a discrete mass. Because benign processes can produce the same broad finding, detecting thickness alone does not identify malignant invasion. no source asserted
  • Benign wall remodelling canManifestAs Intramural cystic spaces empirical high confidence E173 In gallbladder adenomyomatosis, wall remodelling can include intramural sinus spaces that appear cystic when resolved. This provides a benign structural explanation to consider rather than treating every thickened wall as malignancy. no source asserted
  • Acoustic propagation canManifestAs Posterior acoustic effects empirical high confidence E174 Reflection, reverberation and attenuation along the beam path can produce posterior shadows or comet-tail echoes. Such appearances arise from tissue interacting with acquisition and can carry diagnostic information rather than being disposable nuisance texture. no source asserted
  • Neuronal network activity canManifestAs Electrophysiological features empirical high confidence E175 Electrical activity can generate recordable field patterns, but the measured waveform depends on spatial summation, source orientation and recording conditions. Disease need not produce a diagnostic event during the available recording interval. no source asserted

Absence of an edge means not asserted, not false. doesNotEstablish is itself a positive claim of non-entailment, not a claim of incompatibility. None of this determines whether a particular trained model uses a shortcut; that needs an experiment.