Effects of correlation and missing data on sample size estimation in longitudinal clinical trials

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7 Scopus citations

Abstract

In longitudinal clinical trials, a common objective is to compare the rates of changes in an outcome variable between two treatment groups. Generalized estimating equation (GEE) has been widely used to examine if the rates of changes are significantly different between treatment groups due to its robustness to misspecification of the true correlation structure and randomly missing data. The sample size formula for repeated outcomes is based on the assumption of missing completely at random and a large sample approximation. A simulation study is conducted to investigate the performance of GEE sample size formula with small sample sizes, damped exponential family of correlation structure and non-ignorable missing data.

Original languageEnglish (US)
Pages (from-to)2-9
Number of pages8
JournalPharmaceutical Statistics
Volume9
Issue number1
DOIs
StatePublished - Jan 2010

Keywords

  • Damped exponential correlation
  • Missing data
  • Non-ignorable missingness
  • Rates of changes

ASJC Scopus subject areas

  • Statistics and Probability
  • Pharmacology
  • Pharmacology (medical)

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