Video created: May 7, 2013

A meta-analysis summarizes the findings from a collection of relevant studies, providing a more accurate estimate of intervention effectiveness compared to using a single study. These results are usually presented in a “forest plot”. A forest plot provides a graphical depiction of effect size (e.g., small or large) and direction (e.g., positive, negative, or no effect) for each single study included in the meta-analysis and an overall estimate of intervention effectiveness across studies.

Using hypothetical data, this video explains how to interpret forest plots and understand meta-analyses.

The National Collaborating Centre for Methods and Tools is funded by the Public Health Agency of Canada and affiliated with McMaster University. The views expressed herein do not necessarily represent the views of the Public Health Agency of Canada.

NCCMT is one of six National Collaborating Centres (NCCs) for Public Health. The Centres promote and improve the use of scientific research and other knowledge to strengthen public health practices and policies in Canada.