Using other people's data: the ins and outs of secondary data analysis

A variety of types of data ranging from administrative data sets to large-scale surveys have been collected for one purpose but can be accessed and used to address new questions of relevance to primary care. For many research questions, primary data collection isn't necessary because the data already exists. Although relatively few researchers consider analyzing existing data sets, there are a variety of advantages to secondary analysis. This paper introduces the practical aspects of performing secondary analysis. We review the types of questions that can addressed, where and how to access data, and the steps involved in preparing data for analysis.