A mixed methods development of a grit scale for Thai automotive operators

Existing grit measures may not capture how sustained effort and long-term commitment take shape in tightly coupled manufacturing work. This study developed a context-specific grit scale for Thai automotive operators through a sequential exploratory mixed methods design. In the qualitative phase, eight supervisors and senior supervisors with 20 to 35 years of production experience participated in semi-structured interviews. A hybrid deductive-inductive thematic analysis retained the established dimensions of perseverance and passion and identified ten contextual behavioural indicators. Two items were written for each indicator, producing a 20-item pool. Five experts assessed item congruence and clarity, and 30 operators completed a pilot test. In the quantitative phase, 204 operational employees completed the scale, and five items were removed based on combined evidence from the pilot test and confirmatory factor analysis. Using diagonally weighted least squares, a correlated 15-item, two-factor model fit the data well, χ²(89) = 165.45, p < .001, CFI = 0.999, TLI = 0.999, RMSEA = 0.065, 90% CI [0.049, 0.080], and SRMR = 0.038. This model showed better descriptive fit than a one-factor alternative, and both dimensions demonstrated high internal consistency. However, the latent correlation ( r = .938) and HTMT (0.937) indicated that discriminant validity was not established. The findings therefore provide only preliminary support for a highly correlated two-factor measure. Systemic discipline is interpreted as a contextual pattern rather than a separate factor. Independent replication, external validity testing, and measurement invariance are needed before the subscales are interpreted separately or used for high-stakes decisions.