The psychological need satisfaction in exercise scale: An investigation of measurement invariance across groups

Abstract

Given the utility of Basic Psychological Needs Theory (Ryan & Deci, 2002) in exercise contexts (Wilson et al., 2008), an important research priority concerns examining the validity of scores derived from instruments that assess perceptions of competence, autonomy and relatedness in exercise contexts. This investigation examined properties of measurement invariance of scores derived from the Psychological Need Satisfaction in Exercise Scale (PNSE; Wilson et al., 2006). Two groups were examined: (1) individuals living with osteoporosis (N = 220; M= 66.56 years, SD = 10.68) and (2) non-osteoporotic students/staff from a university in Central Canada (N = 283 M = 26.77 years, SD = 9.19). Four nested models with increased equality constraints (Wu, Li, & Zumbo, 2007) were tested using procedures advocated by Jöreskog (2004). Results supported configural and weak invariance of scores from the PNSE (weak invariance: S-Bx2 = 646.99, p < .001, CFI = .98, ? CFI = |.01|, RMSEA = .072 [.065, .079]). As such, the constructs of competence, autonomy and relatedness were construed similarly across groups. However, there was no support for strong invariance (i.e., having the same means and intercepts across groups). Therefore caution should be noted when comparing means of scores derived from the PNSE between groups.

Acknowledgments: Funding for this research was provided by the Social Sciences and Humanities Research Council of Canada