A Trim and Fill Examination of the Extent of Publication Bias in Communication Research

Publication bias can occur when a study is not published in an academic journal because the study did not find a statistically significant result. It can bias meta-analytic estimates upwards because the meta-analyses are missing studies that provide small estimates of the effect size under study. This paper describes the trim and fill technique of estimating the impact of publication bias on meta-analyses (Duval & Tweedie, 2000a, 2000b) and provides a working example. A sample of 68 meta-analyses of communication research were tested for publication bias using the trim and fill technique. The results suggest that most communication meta-analyses are not substantially affected by publication bias.