Developing and validating the WIL-EngDev scale: a measurement tool for assessing English language development in work-integrated learning contexts

This study develop and validate the WIL-English Development Scale (WIL-EngDev) to assess English language development among Thai undergraduates participating in work-integrated learning (WIL) programs. The construct was conceptualized as two dimensions: (1) English skill development from real work experience (WIL-ES) and (2) organizational English support (Org-Support). A six-stage psychometric validation process was conducted to provide validity evidence, including internal structure and relations to variables. Data from 2,115 students were analyzed using split-sample exploratory and confirmatory factor analyses, measurement invariance testing, and one-way ANOVA. The results supported a two-factor structure with strong internal consistency and excellent model fit (CFI = 0.993, TLI = 0.978, RMSEA = 0.051, SRMR = 0.021), as well as acceptable convergent and discriminant validity. Measurement invariance analyses supported configural, metric, and partial scalar invariance across job-function groups, indicating comparable measurement properties. Significant differences were observed in perceived English development and organizational support across job functions, with higher levels reported in hospitality, finance, and marketing contexts than in production or administrative roles. The scale is intended for formative self-assessment of perceived English development, and findings reflect self-reported perceptions rather than objective language gains. Overall, the WIL-EngDev scale contributes to language assessment practice by offering a context-sensitive, theoretically grounded self-assessment tool for workplace-based learning environments.