Statistical Analysis of Repeated Measures in Psychiatric Research

Abstract

• We examined the statistcal methods applide to research studies that used parallel-groups repeated measures designs. Sixty-three of the 343 articles that were published in four major psychiatry research journals during a 6-nonth period contained data of this type. Seven (11%)of the 63 articles applied a multivariata analysis of variance. Four (6%)used a univariate analysis of variance with an adjustment for correlated measures. Ten (16%) used a univariate analysis of variance without an adjustment for correlated measures. Twenty (32%)either reduced their repeated measurements to a single value, such as a maximum-change score in each group, or carried out multiple tests at several time polints. Twenty-two (35%) of the reports did not provide enough information to allow readers to determine the type of anlysis that was applied.We discuss the approspriate selection of analytical techniques for repeated measures designs.