This video explains why systematic reviews are important and how they are done.

(Video prepared by the Cochrane Consumers and Communication Group, La Trobe University and generously support by Cochrane Australia. Written by Jack Nunn and Sophie Hill).

One of the biggest challenges within scientific research is to interpret the results of individual studies in the context of other research that has been done. Although one small study might suggest a treatment works or a substance causes harm, other good-quality studies might have concluded the opposite, so these results need to be looked at together.

A systematic review pools and analyses all relevant and available data to assess the strength of the evidence.

Authors of systematic reviews usually follow detailed quality control guidelines to weed out poor quality studies.

In short, systematic reviews are generally much better at assessing what the evidence tells us than single studies. Note, a systematic review of an area in which there is only weak evidence to review will itself still be quite weak.

Be aware that not everything with ‘review’ in the title is a systematic review – some reviews, like editorial reviews, are less rigorous, and may be open to a scientist picking studies that back-up their point, or including poor quality ones. 

You might also come across the term meta-analysis, which is a statistical method that pools together data from different studies on the same subject, to get the most complete possible picture of the evidence. 

Find our more about systematic reviews in Sense About Systematic Reviews.