For example, classical test theory or the Rasch model call for different procedures.
In all cases, however, the purpose of item analysis is to produce a relatively short list of items (that is, questions to be included in an interview or questionnaire) that constitute a pure but comprehensive test of one or a few psychological constructs.
Researchers apply a variety of statistical procedures to the responses to eliminate unsatisfactory items.
The psychometrician's judgement is required to determine whether the emerging set of items to be retained constitutes a satisfactory test of the target construct.
[citation needed] The three criteria above do not always agree, and a balance must be struck between them in deciding whether or not to include an item.