Assessment of measurement invariance of psychometric tool for pharmaceutical sales executives: implications for social and behavioural pharmacy research

To assess the measurement invariance quality of a short-item employee work assessment questionnaire across key subgroups of pharmaceutical executives. A cross-sectional study with data collected using a nine-item structured questionnaire randomly administered to 406 pharmaceutical executives in Nigeria. Structural equation modelling using Analysis of Moment Structures (AMOS) version 24, and criteria for invariance were absolute change in goodness-of-fit criteria and chi-square test at P < 0.05. Results showed gender [men (n = 293, 72%), women (n = 113, 28%)], [pharmacist (n = 117, 28.8%, non-pharmacist (n = 289, 71.2%)], company type [indigenous (n = 249, 61%), multinational (n = 157, 39%)], and industry experience [low experience; ≤10 years (n = 363, 89%), high experience: ≥10 years (n = 43, 11%)]. Model-fit and construct validity of the instrument were satisfactory. Configural, metric, scalar, and residual invariance of the instrument were confirmed across gender, professional training, and experience levels. Only configural and metric invariance were attained for company type. The developed questionnaire is adequate for assessing pharmacy workforce perception across multiple demographic groups. Invariance testing and reporting are beneficial in social, administrative, and behavioural pharmacy research.