Andrew Yan
Understanding ICH Guidelines: Be Pragmatic, Not Dogmatic
This post is motivated by a disagreement I recently had with a colleague regarding a statistical issue related to the ICH ( International...
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Andrew Yan
Analysis of Covariance: Correlated Covariates
This post continues our previous discussions on statistical issues related to analysis of covariance (ANCOVA), focusing on the impact of...
Andrew Yan
An Angelic Aspect of The Cauchy Distribution
In statistical literature, the Cauchy distribution is notoriously labeled as "evil" or "pathological" because it does not have...
Andrew Yan
Analysis of Covariance: Nonlinear Relationship Between Covariates and Response
It's often claimed that analysis of covariance (ANCOVA) is biased or invalid if a nonlinear relationship exists between covariates and...
Andrew Yan
Analysis of Covariance: Measurement Errors in Covariates
In his excellent book Statistical Issues in Drug Development (2021), Professor Stephen Senn provides a comprehensive overview of...
Andrew Yan
Understanding FDA Recommendations for Covariate Adjustment in Randomized Clinical Trials
In May 2023, the US Food and Drug Administration (FDA) issued final guidance on adjusting for covariates in randomized clinical trials...
Andrew Yan
A Cautionary Note on Correlation Analysis Using Post-Treatment Predictors
When a clinical trial demonstrates positive efficacy results, there is often interest in conducting various post-hoc analyses, including...
Andrew Yan
Bootstrap and Bayesian Inference
You might have heard that the bootstrap procedure can be seen as an approximation of Bayesian inference. This post presents two examples...
Andrew Yan
Simulating Correlated Bernoulli Data
Correlated Bernoulli data are quite common in medical research and clinical trials. In most cases, the correlations between the binary...
Andrew Yan
The Log-Rank Test
Consider a video game played by two teams: 𝑚 boys vs 𝑛 girls. Each player puts $1 on the table (ticket price), then all players start...
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