Garbage in, garbage out

This is a phrase that you may have heard in relation to systematic reviews. What people are worried about is that a reviewer might be collecting together poor quality studies and then presenting the results as if they are high quality. This is a real concern - putting together a group of biased studies is likely to give a biased answer.

So, having selected which studies are included in your review, you need to look at the quality of them.

The topic of quality assessment is covered in depth in Chapter 8 of the Cochrane Handbook for Systematic Reviews of Interventions, so you’ll need your copy close to hand and may want to look at it now.

This module will cover the quality of randomised controlled trials, and not the quality of other study designs.