Assessing inconsistent responding in E and N measures: An application of person-fit analysis in personality

Person-fit analysis assesses the fit of an IRT model at the level of each respondent. This type of assessment allows potentially inconsistent respondents to be detected, and is very relevant in both clinical assessment and validity studies. However, person fit is rarely assessed in IRT-based personality applications. This study assessed person fit in two datasets in which a normal-range personality measure – Neuroticism in one case and Extraversion in the other – had been administered under standard conditions. At the illustrative level, the study shows how person-fit analysis can be performed and how it can be useful in personality measurement. At the substantive level it assesses the frequency and sources of individual misfit. Idiosyncratic interpretation of groups of items, low person reliability, and deliberate sabotaging were identified as sources of misfit. Person-fit measures showed a moderate degree of temporal stability and a significant correlation with a Conscientiousness measure.

► We assessed inconsistent responding in N and E measures by using IRT-based person-fit analysis.
► We show how person-fit analysis can be performed and how it can be useful in personality measurement.
► In both measurements most of the participants respondent consistently.
► Low person reliability, idiosyncratic item interpretation, and sabotaging were sources of misfit.