High Subset Homogeneity Impairs Structural Validity of the Barratt Impulsiveness Scale

Abstract: Problems in providing evidence of structural validity of the Barratt Impulsiveness Scale (BIS) are addressed. As the German translation of a short version of the scale (BIS-15) included pairs of items with highly similar item statements, like the original English version, we hypothesized high subset homogeneity (HSH) as the source of these problems. HSH denotes a situation in which a subset of items shows a larger degree of homogeneity than the remainder of the items of the scale. In a sample of 287 university students, we investigated BIS data by means of confirmatory factor analysis (CFA) models including BIS factors only and models additionally including HSH factors. Whereas the models without HSH factors yielded model misfit, good model fit was observed for the models with HSH factors. These results suggested that BIS items basically showed structural validity, but this validity was impaired by HSH.