Journal of clinical epidemiology
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To determine if the quality of complementary and alternative medicine (CAM) placebo controlled randomized controlled trials (RCTs) is related to the effect sizes they produce when the type of interventions and outcome variables are controlled. ⋯ Possible theoretical reasons for this unexpected positive relationship include (a) sampling error, (b) reduced within group variation, (c) fraudulent reporting, and (d) the restriction of the analyses to placebo controlled trial.
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Randomized controlled trials (RCTs) with dichotomous outcomes may be analyzed with or without adjustment for baseline characteristics (covariates). We studied type I error, power, and potential reduction in sample size with several covariate adjustment strategies. ⋯ We conclude that adjustment for a predictive baseline characteristic may lead to a potentially important increase in power of analyses of treatment effect. Adjusted analysis should, hence, be considered more often for RCTs with dichotomous outcomes.