Differences in assessment of stress and depression and information regarding the timing of stress and depression, is a major challenge for effectively combining the information from the participating studies. The process of data harmonization began with surveys of the contributing studies to determine what key variables were available in each dataset. Based on this information, the consortium judiciously balanced the effort of trying to include as many studies as possible against the most appropriate variables for analysis. Below we describe the two key variables and approaches selected for study.
