JAMA : the journal of the American Medical Association
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To determine if inadequate approaches to randomized controlled trial design and execution are associated with evidence of bias in estimating treatment effects. ⋯ This study provides empirical evidence that inadequate methodological approaches in controlled trials, particularly those representing poor allocation concealment, are associated with bias. Readers of trial reports should be wary of these pitfalls, and investigators must improve their design, execution, and reporting of trials.