The Item analysis purpose is to produce a relatively long list of items which show some degree of face validity.
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. To carry out the analysis, a large pool of candidate items, all of which show some degree of face validity, are given to a large sample of participants who are representative of the target population. 
