How to conduct reliability and validity analysis of questionnaires?

Reliability and validity analysis assess the psychometric quality of questionnaires. Reliability indicates consistency of measurement, while validity reflects accuracy in measuring the intended constructs. These analyses are feasible using statistical software on pilot or main study data. Evaluating reliability typically involves calculating internal consistency, often via Cronbach's alpha (α ≥ 0.7 generally acceptable). Test-retest reliability assesses stability over time. Validity assessment includes examining content validity through expert review, construct validity via exploratory (EFA) or confirmatory factor analysis (CFA) to verify hypothesized factor structures, and criterion validity by correlating with established measures. Crucial prerequisites are sufficient sample size (e.g., ≥10 respondents per item) and a clearly defined theoretical model underlying the constructs. Key principles involve using appropriate statistical tests aligned with measurement goals and interpreting results contextually. Implementation steps entail: pilot testing the questionnaire; gathering data; computing reliability coefficients (e.g., Cronbach's alpha); conducting factor analysis to explore or confirm dimensions; analyzing convergent and discriminant validity (e.g., through multitrait-multimethod matrices or CFA fit indices like CFI/TLI and RMSEA). Iterative refinement is often necessary. This process enhances data credibility, strengthens research findings, and informs instrument refinement for accurate assessment in fields like psychology, education, and health sciences.