Collecting data

This chapter describes approaches that should be used in systematic reviews for collecting data, including extraction of data directly from journal articles and other reports of studies. The data collected for a review should adequately describe the included studies, support the construction of tables and figures, facilitate the risk of bias assessment, and enable syntheses and meta-analyses. Review authors should familiarize themselves with reporting guidelines for systematic reviews to ensure that relevant elements and sections are incorporated. Data collection for systematic reviews should be performed using structured data collection forms. In most cases, it is desirable to collect summary data separately for each intervention group of interest and to enter these into software in which effect estimates can be calculated, such as RevMan. When summary data cannot be obtained from each intervention group, or where it is important to use results of adjusted analyses effect estimates may be available directly.