Testing psychometric properties of the 30-item general health questionnaire.

This study aimed to evaluate the psychometric properties of the General Health Questionnaire (GHQ-30) given conflicting findings in the literature. A cross-sectional, nonexperimental research was used with a convenience sample of 271 American female health care professionals. Data were collected by using self-reported questionnaires. A series of exploratory factor analyses (EFAs), confirmatory factor analyses (CFAs), and structural equation modeling (SEM) were performed to examine underlying dimensions of the GHQ-30. Results from EFAs and CFAs revealed the three-factor composition (positive affect, anxiety, and depressed mood). All factor loadings were statistically significant, and one pair of error variance was allowed to be correlated. All factors contained questionnaire items with acceptable face validity and demonstrated good internal consistency reliability. Results from SEM further confirmed underlying constructs of the scale. To our knowledge, this is the first study that extensively tested the psychometric properties of the GHQ-30, taking both statistical and substantive issues into consideration.