Congruence and measurement invariance of self-report and informant ratings of the Big Five dimensions

The paper presents a study of the Big Five dimensions assessed by the first- and third-person formats of the 50 item IPIP questionnaire. Four-hundred-and-fifty pairs of familiar people (partners or siblings) participated. Relatively high convergent and discriminant validity of both methods was demonstrated in the Multitrait-Multimethod Matrix. Factorial validity of both versions of the 50-item IPIP questionnaire was verified in two separated confirmatory factor analyzes applying the parceling procedure (items were randomly assigned to parcels). The correlated traits - correlated uniqueness (CTCU) model fits joint self-reported and informant ratings data best, suggesting a high level of convergent validity. Other models containing method factors (CTUM, CTCM, CTC(M-1), CTCoM, CTCoUM) do not fit the data so well. The CTCU model is invariant at the metric, scalar, and uniqueness levels. The main limitation of the study is the lack of the possibility to generalize invariance results from parcels to the items.