Once the decision has been made about which articles are to be included in the review, relevant data from each of those studies needs to be extracted. This should be done in a structured, systematic way and will usually be presented in tables in your final review report. Here are some tips:
Your data can be extracted into a simple table, but if you want a more detailed approach, there are a number of analysis tools that can help. See the following:
Sometimes it's difficult to identify the study design of a particular paper. The Centre for Evidence Based Medicine in the UK provides a useful summary of study designs and their characteristics on their website.
This is the section of your review where the findings responding to your initial research question(s), are determined. You will need to develop a synthesis, or critical overview, which integrates the key findings from all the studies you included, while considering the methodological quality and other pertinent features of each of those studies (such as the sample size, population or context in which each one was conducted).