Missing Data

In the psychological literature, the conclusions that can be drawn from empirical research depend on the quality of the data. Consequently, researchers are necessarily concerned with the data collection methods, the measurement of the variables, and the appropriateness of the statistical analyses. In all of these aspects, it is important to consider potential sources of missing data. Missing data can influence the conclusions drawn from a study and, therefore, should be controlled as much as possible. It is generally not possible, however, to completely eliminate missing data from a study. Thus, this entry focuses on the potential impact of missing data on the results of a study as well as ways to address the problems associated with it.