Using Rasch modelling to examine the international personality item pool (IPIP) values in action (VIA) measure of character strengths

This paper investigates the psychometric properties of the values in action (VIA) character strengths (Peterson and Seligman, 2004). A sample of 904 South African undergraduate students (female=77%, male=23%, black=70%, mean age=21.07 years, SD age=2.73 years) was assessed using a 380-item questionnaire that included the items from the international personality item pool (IPIP) values in action (VIA) measure of 24 character strengths as well as additional items based on the underlying theory of the particular constructs. Responses were analysed with the Rasch rating scale model. Reliability coefficients were computed for the retained scale items. The majority (21) of the scales demonstrated satisfactory Rasch model fit and good reliability of scores. The finding that a large proportion of strengths exhibited differential item functioning for at least one of (1) gender, (2) ethnicity and (3) home language group, challenges the assumption that character strengths are necessarily accultural, indicating qualitative distinctions in construct conceptualisations and measurement as a function of emic factors.