Validating the Level of Personality Functioning Scale: We don’t use multimethod research designs

Overreliance on mono-method approaches in research is an issue that compromises increases to measurement validity, confining the utility of our instruments (Bornstein, 2015a; Natoli, in press a). Multimethod approaches, however, often yield more comprehensive and precise data (Ganellen, 2007). Accordingly, multimethod research designs must be utilized when developing and refining measures of personality to make certain that these instruments are truly psychometrically sound. The Level of Personality Functioning Scale (LPFS; APA, 2013) was introduced in DSM-5 and offered to clinicians as a tool to assist in personality disorder diagnosis and to serve as a general tool for measuring personality functioning on a broad continuum. Since its introduction, myriad studies have evaluated the LPFS’s psychometric properties. But at what frequency were mono-method research designs used in studies that purportedly contribute to, or document, this instrument’s psychometric properties? This systematic review demonstrates the lack of multimethod research designs used to evaluate the LPFS’s construct validity. Findings are discussed with regard to the need for multimethod research assessing the psychometric properties of the LPFS and other measures of personality; future directions for doing so are proposed and the unique opportunity offered by the LPFS to initiate a shift in the common practice of instrument validation is acknowledged.