Quasireplication and the contract of error: Lessons from sex ratios, heritabilities and fluctuating asymmetry

Selective reporting-e.g., the preferential publication of results that are statistically significant, or consistent with theory or expectation-presents a challenge to meta-analysis and seriously undermines the quest for generalizations. Funnel graphs (scatterplots of effect size vs. sample size) help reveal the extent of selective reporting. They also allow the strength of biological effects to be judged easily, and they reaffirm the value of graphical presentations of data over statistical summaries. Funnel graphs of published results, including: (a) sex-ratio variation in birds, (b) held estimates of heritabilities, and (c) relations between fluctuating asymmetry and individual attractiveness or fitness, suggest selective reporting is widespread and raise doubts about the true magnitude of these phenomena. Quasireplication-the "replication" of previous studies using different species or systems-has almost completely supplanted replicative research in ecology and evolution. Without incentives for formal replicative studies, which could come from changes to editorial policies, graduate training programs, and research funding priorities, the contract of error will continue to thwart attempts at robust generalizations.