Balance of Group Sizes in Randomized Controlled Trials Published in American Psychological Association Journals

OBJECTIVE: We evaluated whether sample size differences between arms of two-arm parallel group randomized controlled trials (RCTs) published in American Psychological Association (APA)-affiliated journals were consistently smaller than expected by chance with simple randomization. METHOD: We searched PsycINFO for two-arm parallel group RCTs in APA-affiliated journals published January 2007 to September 2017 that used individual randomization …