Missing data refers to a common problem that researchers face in all fields. In the context of testing and survey research, this phenomenon can occur due to participants running out of time, not knowing the correct answer, simply not wanting to answer the question, and even issues within the measurement. In the context of longitudinal research, missing data may result from study attrition. Missing data may also result from simple problems with data entry and management. In short, research paradigms, the phenomenon of missing data, is a potential problem.

The researcher must decide how to deal with missing data prior to using statistical analyses. Many (though not all) such analyses require each variable to be complete prior to its inclusion. If it is not dealt with ...