2.6.3. Goldberg general health questionnaire (GHQ)

This well‐known valid 28‐question instrument with four subscales is scored from 0 to 3 on the Likert scale. Scores range from zero to 84, and lower scores indicate better mental health. ²⁸ The reliability of the questionnaire was confirmed using three methods of test–retest (0.70), split‐half (0.93), and Cronbach's alpha (0.90). The concurrent validity of the instrument, as measured by Middlesex Hospital Questionnaire, was 0.55 (p < 0001). Subscale–total correlations, as another index of validity, were between 0.72 and 0.87. ²⁹ All the participants completed this questionnaire two times before and after the intervention.