Once the data have been extracted and organized, you will need to carefully evaluate what you have found and draw conclusions.
In this step, you describe the characteristics of your studies. What is their quality, their rigor and their scope? What has been studied and what hasn’t? Do the studies agree or disagree with each other? Can you reconcile the disagreements?
You may also decide at this point that some of the studies lack sufficient information or are too poorly designed to use.