All the Same? Different Measures of Personality Functioning Are Similar but Distinct. A Comparative Study from a...

Personality functioning (PF) is a central construct in many theories of personality pathology. Based on psychodynamic theories, two screening questionnaires to assess PF are widely used: The Inventory of Personality Organization-16 item version and the Operationalized Psychodynamic Diagnosis-Structure Questionnaire Short Form. This study aimed to explore the similarities and differences of the two questionnaires in a large clinical sample of N = 1636 psychotherapeutic inpatients. Correlation analyses were conducted to examine the associations between the global scores and between the subscales. The study further used Exploratory Graph Analysis (EGA) to explore the dimensionality of the items. The stability of estimates was evaluated using a bootstrap version of EGA (bootEGA). The results indicated that the two questionnaires are highly correlated, yet not multicollinear, and moderate to large correlations were found between their subscales. EGA revealed six dimensions that fairly represented the original subscales. BootEGA showed that the dimensions and items were stable, except for one item that did not load sufficiently on any dimension. The findings suggest that although the questionnaires are highly correlated, their subscales tap into distinct domains of PF. We discuss implications stemming from these findings for clinical and scientific practice.