Measurement invariance and differential item functioning of the Functionality Appreciation Scale (FAS) in five latin american nations

Abstract

The Functionality Appreciation Scale (FAS) is increasingly used within diverse national and linguistic contexts, but assessments of its functioning across groups remains limited. To extend knowledge, we examined measurement invariance of the FAS across five Latin American nations (Argentina, Chile, Colombia, Mexico, Uruguay), with 1861 respondents. We also assessed differential item functioning (DIF) across respondent characteristics, as well as associations between functionality appreciation and life satisfaction. Confirmatory factor analysis supported a unidimensional structure of the FAS in all national groups, but constraints on a small number of intercepts and uniquenesses had to be relaxed to achieve partial invariance. Likewise, respondent gender, age, and body mass index (BMI) differentially affected some item functioning across national groups, but relaxing constraints on non-invariant paths allowed us to achieve partial DIF. There were no differences in latent functionality appreciation across nations, while men, older participants, and those with lower BMIs had higher functionality appreciation in all national groups. Finally, greater functionality appreciation was robustly associated with higher life satisfaction, with the association being invariant across nations. Further research should assess reasons for non-invariance of some items of the FAS in Latin America, ideally through the use of follow-up qualitative research.