Published methodological quality of randomized controlled trials does not reflect the actual quality assessed in protocols.

Objectives: To assess whether the reported methodological quality of randomized controlled trials (RCTs) reflects the actual methodological quality and to evaluate the association of effect size (ES) and sample size with methodological quality.

Study Design And Setting: Systematic review. This is a retrospective analysis of all consecutive phase III RCTs published by eight National Cancer Institute Cooperative Groups up to 2006.

Optimism bias leads to inconclusive results-an empirical study.

Objective: Optimism bias refers to unwarranted belief in the efficacy of new therapies. We assessed the impact of optimism bias on a proportion of trials that did not answer their research question successfully and explored whether poor accrual or optimism bias is responsible for inconclusive results.

Study Design: Systematic review.