Person-fit analysis

Person-fit analysis is a technique for determining if the person's results on a given test are valid.

The purpose of a person-fit analysis is to detect item-score vectors that are unlikely given a hypothesized test theory model or unlikely compared with the majority of item-score vectors in the sample.

In individual decision-making in education, psychology, and personnel selection, it is critically important that test users can have confidence in the test scores used. The validity of individual test scores may be threatened when the respondent's answers are governed by factors other than the psychological trait of interest. Person-fit methods are used to detect item-score vectors that are unlikely given the test-theory model that describes the data, and as a result, indicate invalid measurement.