Transtheoretical model constructs for physical activity behavior are invariant across time among ethnically diverse adults in Hawaii

ObjectivesTo test the measurement properties of the Transtheoretical Model (TTM) relative to physical activity (PA) behavior.DesignParticipants from an ethnically diverse sample in Hawaii (N = 700) completed questionnaires capturing each TTM construct.MethodThe current study examined the factorial validity and longitudinal invariance of TTM constructs recently revised for PA.ResultsFactorial validity was confirmed for each construct using confirmatory factor analysis with full-information maximum likelihood. Longitudinal invariance was evidenced across a shorter (3-month) and longer (6-month) time period via nested model comparisons.ConclusionsThe questionnaires for each validated TTM construct are provided, and can now be generalized across similar subgroups and time points. Further validation of the provided measures is suggested in additional populations and across extended time points.

► In this study we confirm factorial validity for each Transtheoretical Model construct. ► The Transtheoretical constructs were found invariant across 3- and 6-month time periods. ► The questionnaire for each validated Transtheoretical Model construct is provided.