What is "funnel plot"

n. (context statistics English) A scatterplot of effect size against a measure of study size or variablity, used primarily as a visual aid to detecting and displaying bias or systematic heterogeneity.

A funnel plot is a graph designed to check for the existence of publication bias; funnel plots are commonly used in systematic reviews and meta-analyses. In the absence of publication bias, it assumes that the largest studies will be plotted near the average, and smaller studies will be spread evenly on both sides of the average, creating a roughly funnel-shaped distribution. Deviation from this shape can indicate publication bias.