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Ignorability and bias in clinical trials
Author(s) -
Heitjan Daniel F.
Publication year - 1999
Publication title -
statistics in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.996
H-Index - 183
eISSN - 1097-0258
pISSN - 0277-6715
DOI - 10.1002/(sici)1097-0258(19990915/30)18:17/18<2421::aid-sim266>3.0.co;2-r
Subject(s) - parametric statistics , clinical trial , drop out , econometrics , computer science , missing data , statistics , medicine , mathematics , economics , machine learning , pathology , demographic economics
Patient non‐compliance and drop‐out can bias analyses of clinical trial data. I describe a parametric model for treatment cross‐over and drop‐out and demonstrate how the concept of ignorability, originally defined for incomplete‐data problems, can elucidate sources of bias in clinical trials. I discuss some implications of the theory and present simulation examples that illustrate the potential effects of non‐ignorable cross‐over and drop‐out on bias and power. Copyright © 1999 John Wiley & Sons, Ltd.