Psychometric Evaluation of Mindfulness in Teaching Scale: Measurement Invariance in Educational Level and Age

Background: This study examined the factorial structure and measurement invariance of the Mindfulness in Teaching Scale (MTS) among 735 Iranian teachers, comprising 370 primary and 365 secondary school teachers, aged 24 to 55. Objectives: To evaluate the psychometric attributes and validity of the MTS within educational settings, employing confirmatory factor analysis (CFA) alongside the LMS to ascertain convergent validity and scrutinize measurement invariance across varying educational levels and age groups, thereby ensuring that the scale uniformly quantifies mindfulness among diverse populations. Methods: Using multi-group confirmatory factor analysis (CFA) with AMOS-24, the study validated the MTS’s dual-factor model, which includes intrapersonal and interpersonal mindfulness, across the entire sample, as well as various educational levels and age groups. Results: The model fit indices demonstrated satisfactory alignment for the aggregate sample and across different educational levels and age classifications, meeting established criteria including Comparative Fit Index (CFI) (0.90), root mean square error of approximation (RMSEA) (< 0.08), and χ2/df ratios (< 3.0). All factor loadings exceeded 0.30 (P < 0.05), affirming the scale’s structure and consistency with its original design. The reliability of the MTS and its subscales was acceptable, ranging from 0.68 to 0.85. Additionally, the MTS showed metric and scalar invariance for age groups [Δχ2 values of 19.25 (Δdf = 12; P > 0.05) and 7.33 (Δdf = 5; P > 0.05)], and for educational levels, the metric and scalar invariance models [Δχ2 of 6.75 (Δdf = 12; P > 0.05) and Δχ2 of 22.36 (Δdf = 14; P > 0.05)], supporting consistent measurement across subgroups. Furthermore, a positive correlation (r = 0.23, P < 0.05) with the Langer Mindfulness Scale (LMS) supported its validity. Conclusions: The study suggests that the MTS is a reliable and valid tool for assessing mindfulness among primary and secondary school teachers in Iran.