Statistics - explanations and formulas

Forest Plots

statistical data represented using Forest Plot graphics   

The forest plot is a key way researchers can summarize data from multiple papers in a single image.

In a typical forest plot, the results of the studies used in the review are shown as squares centered on the point estimate of the result of each study.

A horizontal line runs through the square to show its confidence interval—usually, a 95% confidence interval.

The overall estimate from the meta-analysis and its confidence interval are put at the bottom, represented as a diamond. The center of the diamond represents the pooled point estimate, and its horizontal tips represent the confidence interval. Significance is achieved at the set level if the diamond is clear of the line of no effect.  If the diamond crosses over the horizontal line, then there is no significant effect between the two interventions.

The plot allows readers to get a visual representation as to the variation between the study results included in a meta-analysis.