Commitment to Self-Tracking Among Wearable-Device Users: Validation of the C2ST Scale and Known-Groups Evidence

Commitment to self-tracking refers to the extent to which individuals are dedicated to the practice of wearable- and app-based self-monitoring. This commitment is behaviorally grounded and captures users' sustained investment in wearable and app-based self-monitoring. The objective of this study was to validate the Commitment to Self-Tracking (C2ST) scale in Czechia by examining its dimensionality, confirmatory model fit, reliability, and known-groups evidence among self-tracking device users.

The results were obtained from a face-to-face survey of a sample of 502 self-tracking device users who were recruited from the Czech general population using address-based sampling. The sample was randomly split into two subsamples for exploratory factor analysis (EFA) and confirmatory factor analysis (CFA). Item- and scale-level descriptive statistics and internal consistency (Cronbach's α, McDonald's ω) were calculated. The EFA was utilized to evaluate the factorability and latent structure of the model, and the CFA was employed to assess the model's fit. The known-groups validity was examined using nonparametric group comparisons (Kruskal-Wallis H and Mann-Whitney U tests) with theoretically relevant external indicators, such as social comparison orientation, willingness to share data, perceived usefulness of tracking, and self-rated health.

The C2ST score demonstrated a full range of theoretical variation, exhibiting minimal floor (7.2%) and ceiling (2.0%) effects and a nearly symmetrical distribution. The internal consistency of the scale was found to be high (α = 0.968; ω = 0.968), and the corrected item-total correlations were uniformly high. The EFA supported a single-factor solution that explained 74.4% of the variance. The CFA model demonstrated a unidimensional structure, indicating that the observed variables were best explained by a single factor. An improved model attained an adequate-to-excellent fit (RMSEA = 0.051; SRMR = 0.018; CFI = 0.991; TLI = 0.986) and accounted for substantial item variance (R² = 0.60-0.82). The known-groups validity was supported by pronounced differences in C2ST scores across social comparison and data-sharing orientations, as well as perceived usefulness of tracking for health and training goals (all p < 0.001).

The Czech C2ST has been demonstrated to exhibit high reliability and a clear, unidimensional structure. Additionally, it exhibited robust CFA support and theory-consistent known-groups validity among self-tracking device users. The scale is appropriate for research on self-tracking commitment and persistence.