The horizontal location of the dot or square on the graph represents the measure of the effect. The findings of each study are plotted as one dot or square, enabling readers to obtain a visual impression of similarities and differences in findings between studies.

The exposure can also be a variable that is not environmental-for instance age, sex, ethnicity, or a gene allele. In a systematic review of epidemiological studies, the forest plot shows whether the exposure (e.g., smoking, alcohol, inhaling high levels of air pollutants, obesity) is likely to be a cause of the outcome measure (e.g., development of a medical condition). The effectiveness is expressed as the outcome measure: elimination of the pathogen from the body, recovery from the disease, or discharge from the hospital within a set number of days. In a systematic review of clinical trials, for example, the forest plot shows whether the intervention/new drug is more effective than the control/standard treatment.

Software makes forest plots easier to work with Where is a forest plot used?

Graphpad prism 8 number at risk table