Development and validation of a method for deriving MMPI-3 scores from MMPI-2/MMPI-2-RF item responses

The Minnesota Multiphasic Personality Inventory-3 (MMPI-3; Ben-Porath & Tellegen, 2020a) was developed to expand the content coverage of the MMPI-2-Restructured Form (MMPI-2-RF; Ben-Porath & Tellegen, 2008/2011) and to update the test's norms to better represent the U.S. population. Because most MMPI-3 items were carried over from the MMPI-2-RF, most MMPI-3 scales can be either fully scored or prorated from the MMPI-2/MMPI-2-RF item pool. We describe development of a procedure for deriving MMPI-3 scores from MMPI-2/MMPI-2-RF protocols and examine the psychometric properties of prorated MMPI-3 scores across various samples. Following Tarescavage et al. (2016), who developed a method for prorating most MMPI-2-RF scores from the original MMPI, prorated MMPI-3 scales had to meet three criteria: (a) sufficient representation in the MMPI-2-RF item pool, (b) association with the full-length corresponding MMPI-3 scale at r ≥ .90 in multiple samples, and (c) comparable T score means and standard deviations in multiple samples. These criteria resulted in the exclusion of the three MMPI-3 non-content-based Validity Scales, as well as nine Specific Problems Scales, yielding 16 MMPI-3 scales that can be fully scored and 24 for which psychometrically comparable prorated score estimates can be derived from responses to the MMPI-2 or MMPI-2-RF item pools. Evidence of the psychometric functioning of the resulting scale scores and their comparability with the full versions of these scales across samples is presented and discussed. This procedure provides a means to study 40 of the 52 MMPI-3 scales using archival data obtained with older versions of the inventory. (PsycInfo Database Record (c) 2024 APA, all rights reserved).