Casewise deletion

One of the options or methods available to a researcher in treating the missing responses from the filled up questionnaires. In this option, cases, or respondents, with any missing responses are discarded from the analysis. Because many respondents may have some missing responses, this approach could result in a small sample. Throwing away large amounts of data is undesirable, because it is costly and time consuming to collect data. Furthermore, respondents with missing responses could differ from respondents with complete responses in systematic ways. If so, caswise deletion could seriously bias the results of the study.