Well-being as a moving target: Measurement equivalence of the Bradburn Affect Balance scale

Although the Bradburn Affect Balance scale (ABS) is a frequently used two-f actor indicator of well-being in later life, its measurement and invariance properties are not well documented. We examined these issues using confirm atory factor analyses of cross-sectional (adults ages 54-87 years) and long itudinal data from the victoria Longitudinal Study. Stability of the positi ve and negative affect factors was moderate across a 3-year period. overall , factor loadings For positive affect items were invariant over time with t he exception of the pleased item. Negative affect items were time invariant . However, age-group comparisons between young-old and old-old groups revea led age differences in loadings for the upset item at Time 1. Finally, gend er groups differed in loadings for the fop of the world and going your way items. Thus a pattern of partial measurement equivalence characterized item response to the ABS. Our results suggest that group comparisons and longit udinal change in ABS scale scores of positive and negative affect should be interpreted with caution.