Publication Bias in Meta-Analysis

Publication bias is the term in which the research that appears in the literature is unrepresentative of the population of completed studies. In a meta-analysis, the studies selected and included are vital to draw a valid conclusion. When only the studies that demonstrate statistical significance or, if not statistically significant, don't reflect qualitative interaction of a drug are included in a meta-analysis, publication bias may occur. In this chapter, we offer some aspects of the publication bias problem in meta-analysis. In particular, we discuss its impact on meta-analysis results. We also discuss how to deal with some of the issues that impact meta-analysis due to publication bias. We investigate how to test for publication bias. Illustrations in R and Stata systems using real studies are presented.