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Causal Inference

Everything on Aqrab tagged Causal Inference — grouped into one landing page so readers can go deeper by problem family instead of bouncing around the archive blind.

Causal InferenceMediation AnalysisMethods Critique

Treatment-Induced Mediator-Outcome Confounding: When Mediation Analysis Starts Chasing the Consequences of Treatment

A practical guide to treatment-induced mediator-outcome confounding for clinical researchers. Covers why natural direct and indirect effects fail when treatment changes later severity, toxicity, adherence, or surveillance that affect both the mediator and outcome.

2026-06-18·16 min read
Causal InferenceReal-World EvidencePolicy Evaluation

Stochastic Interventions: When “Treat Everyone” Is Not the Policy Question

A practical guide to stochastic interventions for clinical researchers. Covers when deterministic treatment rules become unrealistic, how probability-shift interventions preserve positivity, and what reviewers should demand before trusting policy-effect claims.

2026-06-03·16 min read
Causal InferenceReal-World EvidenceMethods Critique

Calendar Time Confounding: When Secular Trends Pretend Your Intervention Worked

A practical guide to calendar time confounding for clinical researchers. Covers secular trends, treatment diffusion, concurrent comparators, and what reviewers should demand before trusting real-world benefit that may just reflect a later era.

2026-05-22·16 min read
Causal InferencePharmacoepidemiologyStudy Design

Prevalent-User Bias: When Your Drug Study Starts After the Interesting Harm Already Happened

A practical guide to prevalent-user bias for clinical researchers. Covers depletion of susceptibles, survivor selection, post-treatment baseline covariates, and what reviewers should demand before trusting late-entry treatment cohorts.

2026-05-18·16 min read
Causal InferenceTarget Trial EmulationStudy Design

Clone-Censor-Weight: The Target Trial Fix That Still Breaks When You Use It Casually

A practical guide to clone-censor-weight for clinical researchers. Covers when the design is needed, how cloning and artificial censoring work, where immortal time bias reappears, and what reviewers should demand before trusting a target trial emulation.

2026-05-16·16 min read
Causal InferenceClinical EpidemiologyEffect Measures

Noncollapsibility of Odds Ratios: Why Adjustment Can Change the Number Even When Confounding Did Not

A practical guide to noncollapsibility of odds ratios for clinical researchers. Covers why crude and adjusted odds ratios can differ without confounding, when logistic regression invites over-interpretation, and what reviewers should demand instead.

2026-05-13·16 min read
Causal InferenceTrial DesignClinical Trials

Composite Endpoints: When One Trial Outcome Quietly Becomes Four Different Clinical Questions

A practical guide to composite endpoints for clinical researchers. Covers when endpoint bundles improve efficiency, when they distort clinical meaning, how soft components hijack results, and what reviewers should demand before trusting the headline.

2026-05-12·15 min read
Causal InferenceEstimandsTrial Design

Per-Protocol Effects: The Estimand Everyone Wants and the Bias Trap They Usually Build

A practical guide to per-protocol effects for clinical researchers. Covers sustained-adherence estimands, naive as-treated failure, selection bias after protocol deviation, and what reviewers should demand before trusting per-protocol claims.

2026-05-11·15 min read
Causal InferenceClinical AIStudy Design

Prediction vs Causation: Why Your Best Risk Model Still Cannot Tell You What to Treat

A practical guide for clinical researchers on the difference between prediction and causation. Covers why strong risk models do not identify treatment effects, how to frame the right estimand, and what reviewers should flag in AI-driven clinical studies.

2026-05-10·15 min read
Causal InferenceSurvival AnalysisRMST

Restricted Mean Survival Time: When Hazard Ratios Are Not the Clinical Answer

A practical guide to restricted mean survival time for clinical researchers. Covers what RMST estimates, when it beats the hazard ratio, how to choose the time horizon, and how to report results clinicians can actually interpret.

2026-05-09·15 min read
Causal InferenceSurvival AnalysisLandmark Analysis

Landmark Analysis: Useful, Honest, and Frequently Overclaimed

A practical guide to landmark analysis for clinical researchers. Covers delayed treatment, immortal time bias, conditional survivor populations, landmark selection, and why a cleaner timeline still changes the causal question.

2026-05-08·15 min read
Causal InferenceTMLEMachine Learning

Targeted Maximum Likelihood Estimation: Doubly Robust, Not Doubly Forgiving

A practical guide to targeted maximum likelihood estimation for clinical researchers. Covers nuisance models, clever covariates, machine learning, overlap diagnostics, and why TMLE is robust in theory but never permission to stop thinking.

2026-05-07·16 min read
Causal InferenceCase-Crossover DesignStudy Design

Case-Crossover Design: When Patients Become Their Own Controls

A practical guide to case-crossover designs for clinical researchers. Covers self-matching, hazard versus control windows, transient exposures, protopathic bias, time trends, and when this elegant design is exactly right or exactly wrong.

2026-05-04·15 min read
Causal InferenceMissing DataStudy Design

Multiple Imputation: Missing Data Does Not Become Innocent Because MICE Ran

A practical guide to multiple imputation for clinical researchers. Covers MICE, complete-case failure, MAR versus MNAR, imputation-model design, and why missing data needs causal thinking instead of software ritual.

2026-05-03·16 min read
Causal InferenceG-ComputationStandardization

G-Computation: Predict the Outcome Under Each Treatment Strategy

A practical guide to g-computation for clinical researchers. Covers counterfactual prediction, standardization, outcome modeling, positivity, model misspecification, and how to estimate causal effects by averaging predicted outcomes under competing interventions.

2026-05-02·15 min read
Causal InferenceEstimandsStudy Design

Estimands: The Causal Question You Should Define Before Running the Analysis

A practical guide to estimands for clinical researchers. Covers treatment strategies, intercurrent events, target populations, summary measures, and why many studies fail because they never define the actual causal question clearly.

2026-05-01·16 min read
Causal InferenceTime-Varying ConfoundingLongitudinal Data

Time-Varying Confounding: When Yesterday's Treatment Changes Today's Confounder

A practical guide to time-varying confounding for clinical researchers. Covers treatment-confounder feedback, why ordinary regression fails, and how MSMs, g-methods, and target trial logic handle evolving treatment decisions.

2026-04-29·16 min read
Causal InferenceSurvival AnalysisMissing Data

Informative Censoring: When Dropout Is Part of the Bias

A practical guide to informative censoring for clinical researchers. Covers loss to follow-up, treatment discontinuation, database exit, inverse probability of censoring weights, and why dropout can bias survival and causal estimates when it depends on prognosis.

2026-04-28·16 min read
Causal InferencePharmacoepidemiologySelf-Controlled Designs

Self-Controlled Case Series: When Each Patient Becomes Their Own Control

A practical guide to self-controlled case series for clinical researchers. Covers transient exposures, acute outcomes, fixed-confounding control, event-dependent exposure, and why within-person designs still live or die on timing assumptions.

2026-05-06·16 min read
Causal InferenceMeasurement ErrorBias Diagnostics

Measurement Error: When Bad Variables Break Good Causal Methods

A practical guide to measurement error for clinical researchers. Covers noisy exposures, weak confounder proxies, surveillance-driven outcomes, validation strategies, and why sophisticated causal methods cannot rescue bad variables.

2026-04-30·16 min read
Causal InferenceSurvival AnalysisClinical Outcomes

Competing Risks: When Kaplan-Meier Tells the Wrong Clinical Story

A practical guide to competing risks for clinical researchers. Covers death and discharge as competing events, why Kaplan-Meier can overstate event probability, and how cause-specific hazards and cumulative incidence answer different clinical questions.

2026-04-27·16 min read
Causal InferenceBias DiagnosticsObservational Studies

Bias Amplification: When Adjustment Makes Unmeasured Confounding Worse

A practical guide to bias amplification for clinical researchers. Covers near-instruments, noisy severity proxies, treatment-prediction traps, and why the wrong adjustment variable can magnify residual confounding instead of reducing it.

2026-04-26·15 min read
Causal InferenceMeasurement ErrorBias Diagnostics

Misclassification Bias: When Your Variables Lie Before the Model Starts

A practical guide to misclassification bias for clinical researchers. Covers wrong exposure and outcome labels, weakly measured confounders, surveillance-driven event detection, and why bad variables can distort causal estimates before modeling even begins.

2026-04-25·16 min read
Causal InferencePharmacoepidemiologyStudy Design

Active Comparator New-User Design: The Observational Study Upgrade Most Drug Papers Need

A practical guide to the active comparator new-user design for clinical researchers. Covers why treated-versus-untreated comparisons fail, how new-user cohorts reduce prevalent-user bias, how active comparators narrow confounding by indication, and what reviewers should demand before trusting comparative effectiveness claims.

2026-04-24·16 min read
Causal InferenceSelection BiasObservational Studies

Selection Bias: When Your Study Sample Is the Problem

A practical guide to selection bias for clinical researchers. Covers referral filtering, survivor bias, complete-case analysis, informative loss to follow-up, collider-driven selection, and why a clean model cannot rescue a distorted sample.

2026-04-23·16 min read
Causal InferenceConfounding by IndicationObservational Studies

Confounding by Indication: When Sicker Patients Make Treatments Look Dangerous

A practical guide to confounding by indication for clinical researchers. Covers treatment selection, severity-driven prescribing, contraindication bias, why routine adjustment often fails, and how to design observational comparisons that do not confuse prognosis with treatment effect.

2026-04-22·16 min read
Causal InferenceImmortal Time BiasStudy Design

Immortal Time Bias: The Fake Survival Advantage Hiding in Bad Study Design

A practical guide to immortal time bias for clinical researchers. Covers time zero, future-based exposure definitions, delayed treatment initiation, target trial emulation, and why you cannot adjust your way out of a broken timeline.

2026-04-21·16 min read
Causal InferenceInterrupted Time SeriesPolicy Evaluation

Interrupted Time Series: Strong Quasi-Experiments Need More Than a Before-and-After Plot

A practical guide to interrupted time series for clinical researchers. Covers level and slope changes, segmented regression, seasonality, autocorrelation, controlled ITS designs, and why a vertical line on a chart is not a causal estimate.

2026-04-20·16 min read
Causal InferenceG-FormulaLongitudinal Data

Parametric G-Formula: Estimating Causal Effects When Covariates Change Over Time

A practical guide to the parametric g-formula for clinical researchers. Covers time-varying confounding, dynamic treatment strategies, longitudinal simulation, model diagnostics, and why ordinary regression breaks when covariates are changed by prior treatment.

2026-04-19·17 min read
Causal InferenceUnmeasured ConfoundingObservational Studies

Proximal Causal Inference: What to Do When Unmeasured Confounding Is Still on the Table

A practical guide to proximal causal inference for clinical researchers. Covers proxy variables, treatment-inducing versus outcome-inducing proxies, bridge functions, completeness, and why this method is powerful but brutally assumption-heavy.

2026-04-18·17 min read
Causal InferencePositivityPropensity Scores

Positivity & Overlap: The Assumption Your Causal Estimate Cannot Survive Without

A practical guide to positivity and overlap for clinical researchers. Covers common support, extreme weights, trimming, overlap-focused estimands, and why many causal analyses fail because treated and untreated patients barely resemble each other.

2026-04-17·15 min read
Causal InferenceExternal ValidityStudy Design

Transportability & External Validity: When Your Causal Estimate Travels, and When It Absolutely Does Not

A practical guide to transportability and external validity for clinical researchers. Covers target populations, effect heterogeneity, trial selection, overlap, reweighting, and why “generalizable” is usually a lazy claim unless you prove the estimate can actually travel.

2026-04-16·16 min read
Causal InferenceCollider BiasSelection Bias

Collider Bias: How Adjustment Can Manufacture Associations

A practical guide to collider bias for clinical researchers. Covers common-effect conditioning, Berkson bias, selected cohorts, complete-case traps, and why the wrong adjustment set can literally manufacture a result.

2026-04-15·15 min read
Causal InferenceInterferenceStudy Design

Interference & Spillover Effects: When One Patient's Treatment Changes Another's Outcome

A practical guide to interference and spillover effects for clinical researchers. Covers SUTVA violations, direct versus indirect effects, partial interference, cluster and network designs, and why contamination is often the estimand trying to get your attention.

2026-04-14·16 min read
Causal InferencePrincipal StratificationTrial Interpretation

Principal Stratification: Estimating Effects When Post-Treatment Variables Matter

A practical guide to principal stratification for clinical researchers. Covers compliers, always-takers, truncation by death, latent strata, CACE/LATE, and why conditioning on observed post-treatment subgroups is usually causal self-sabotage.

2026-04-13·16 min read
Causal InferenceBias DiagnosticsDAGs

Overadjustment Bias: When More Covariates Make Causal Inference Worse

A practical guide to overadjustment bias for clinical researchers. Covers mediators, colliders, post-treatment variables, propensity score misuse, and why the biggest adjustment set is often the least credible one.

2026-04-12·15 min read
Causal InferenceIdentificationDAGs

Front-Door Criterion: The Causal Backdoor Alternative Nobody Uses Enough

A practical guide to the front-door criterion for causal inference. Covers full mediation, mediator-outcome confounding, identification logic, DAG requirements, and why most real datasets are nowhere near clean enough for a credible front-door design.

2026-04-11·16 min read
Causal InferenceBias DiagnosticsObservational Studies

Negative Controls: The Bias Check Most Observational Studies Skip

A practical guide to negative control outcomes and exposures for clinical researchers. Covers residual confounding, selection bias, surveillance bias, falsification endpoints, and how to interpret a failed negative control without lying to yourself.

2026-04-10·15 min read
Causal InferenceDAGsStudy Design

DAG Construction: How to Draw a Causal Graph Before You Touch the Model

A practical guide to DAG construction for clinical researchers. Covers time ordering, node selection, confounders vs mediators vs colliders, minimally sufficient adjustment sets, and why most covariate lists are just causal confusion wearing a regression badge.

2026-04-09·17 min read
Causal InferenceMediation AnalysisMechanisms

Mediation Analysis: When You Want the Mechanism, Not Just the Effect

A practical guide to mediation analysis for clinical researchers. Covers direct and indirect effects, mediator-outcome confounding, treatment-induced confounding, interventional effects, and why most mediator-adjusted regressions are wrong.

2026-04-08·16 min read
Causal InferenceG-EstimationLongitudinal Data

G-Estimation: The Causal Method You Reach For When Time-Varying Confounding Breaks Regression

A practical guide to g-estimation and structural nested models for clinical researchers. Covers treatment-confounder feedback, blipped-down outcomes, identifying assumptions, and when g-estimation beats naive longitudinal regression or unstable weights.

2026-04-07·17 min read
Causal InferenceMachine LearningHeterogeneous Effects

Causal Forests: Finding Treatment Effect Heterogeneity Without Fooling Yourself

A practical guide to causal forests for estimating who benefits more, less, or not at all. Covers CATEs, honest splitting, overlap, validation, clinical use cases, and the reporting standards reviewers should expect.

2026-04-06·16 min read
Causal InferenceSensitivity AnalysisUnmeasured Confounding

E-values & Sensitivity Analysis: How to Stress-Test Causal Claims

A practical guide to the one question every observational study must answer: how strong would an unmeasured confounder have to be to erase your result? Covers E-values, confidence-limit interpretation, Rosenbaum bounds, negative controls, and the reporting language reviewers trust.

2026-04-05·16 min read
Causal InferenceMendelian RandomizationGenetic Epidemiology

Mendelian Randomization: Using Genetics as Nature's Randomized Trial

How genetic variants serve as natural instruments for causal inference — and why horizontal pleiotropy, population stratification, and weak instruments break most published MR studies. Covers two-sample MR, MR-Egger, MR-PRESSO, and the STROBE-MR reporting checklist.

2026-04-04·16 min read
Causal InferenceMSMTime-Varying Confounding

Marginal Structural Models: A Practical Guide for Clinical Researchers

How MSMs use stabilized inverse probability weights to handle time-varying confounders — the ones that change over time and are affected by prior treatment. Covers weight estimation, model fitting, clinical examples, and common pitfalls.

2026-04-02·17 min read
Causal InferenceDAGsCausal Framework

Structural Causal Models & DAGs: A Practical Guide for Clinical Researchers

The causal framework behind every method you use. Covers DAGs, d-separation, do-calculus, backdoor/frontdoor criteria, mediation analysis, and how to draw the graph that makes your analysis work.

2026-04-02·18 min read
Causal InferenceIPWPropensity Scores

Inverse Probability Weighting: When PSM Discards Your Data

Why IPW outperforms matching by keeping all patients — and how extreme weights, positivity violations, and wrong variance estimators break published analyses silently.

2026-04-02·15 min read
Causal InferenceMachine LearningHigh-Dimensional Data

Double Machine Learning: A Practical Guide for Clinical Researchers

How DML uses machine learning to estimate causal effects while controlling for high-dimensional confounders. Covers cross-fitting, Neyman orthogonality, clinical applications, and implementation in EconML.

2026-04-01·15 min read
Causal InferenceTarget Trial EmulationStudy Design

Target Trial Emulation: A Practical Guide for Clinical Researchers

The framework that bridges observational data and causal claims — by asking what RCT you wish you had. Covers protocol specification, time zero alignment, clone-censor-weight, immortal time bias, and reporting.

2026-03-30·16 min read
Causal InferenceRDDQuasi-Experimental

Regression Discontinuity Design: A Practical Guide for Clinical Researchers

RDD turns arbitrary thresholds into causal evidence. Covers sharp vs fuzzy designs, bandwidth selection, manipulation testing, clinical applications, and a complete reporting checklist.

2026-03-29·14 min read
Causal InferenceSynthetic ControlPolicy Evaluation

Synthetic Control Methods: Building Counterfactuals When DID Fails

How to construct a synthetic twin from donor pools when parallel trends don't hold. Covers SCM optimization, validation via placebo tests, modern extensions (ASCM, SDID), and common pitfalls.

2026-03-28·16 min read
Causal InferenceDIDPolicy Evaluation

Difference-in-Differences: A Practical Guide for Clinical Researchers

When and how to use DID in clinical research. Covers parallel trends, staggered adoption, common pitfalls, reporting checklist, and modern estimators.

2026-03-27·15 min read
Causal InferenceInstrumental VariablesUnmeasured Confounding

Instrumental Variables: When Observational Data Meets Unmeasured Confounding

When PSM and regression fail because of unmeasured confounding, IV methods offer a way forward. A practical guide covering instruments, LATE, Mendelian randomization, and the exclusion restriction.

2026-03-26·14 min read
Causal InferencePSMObservational Studies

Propensity Score Matching: A Practical Guide for Clinical Researchers

What PSM actually does, when it fails, and how to report it correctly. Written for researchers who want to use it — not just cite it.

2026-03-26·12 min read

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