Reliability of health belief indexes: confirmatory factor analysis in sex, race, and age subgroups

Despite frequent reference to the Health Belief Model (HBM), few studies address the internal consistency (within questionnaires) or the stability across populations of scales used to measure HBM variables. As part of a 1983 Michigan statewide blood pressure survey, trained interviewers administered 32 health belief questionnaire items to 2,802 randomly selected adult Michigan residents. Exploratory common factor analysis was used to examine the structure of these questionnaire items. Six correlated factors, which corresponded closely with theoretical constructs, appeared. Guided by these results, we developed a confirmatory common factor model. The model's fit was examined in random population halves and in univariate sex, race, and age subgroups. Except perhaps in the oldest age group, the model's fit appeared constant. Reliabilities estimated for HBM factor scales formed with these questionnaire items appeared independent of age, race, or sex.