Internal consistency and test-retest reliability of the Chinese version of the 5-item Duke University Religion Index

BACKGROUND: The Duke University Religion Index (DUREL) is a widely-used 5-item scale assessing religiosity. AIM: Assess the internal consistency, reliability, and factor structure of the revised Chinese version of DUREL. METHODS: Using probability proportionate to size (PPS) methods we randomly identified 3981 households with eligible occupants in 20 primary sampling sites in Ningxia Hui Autonomous Region, a province in northwest China in which 34% of the population are Muslims of the Hui ethnic group. In 3054 households a screening interview was completed and an adult family member was randomly selected; 2425 respondents completed the survey (including the DUREL) and 188 randomly selected individuals repeated the survey an average of 2.5 days later. RESULTS: The internal consistency (Cronbach’s α) of the 5 items in the full sample was 0.90; it ranged from 0.70 to 0.90 in various subgroups of subjects stratified by ethnicity, urban versus rural residence, and above versus below median education. The test-retest reliability (intraclass correlation coefficient) for the total score in the full sample was 0.87; it ranged from 0.63 to 0.90 in the different subgroups of subjects. Exploratory factor analysis in a random half of the sample identified a single factor (eigen value=4.21) that explained 84% of the total variance. Confirmatory factor analysis in the second half of the sample confirmed the unidimensional model; the model fit measures of the one-factor model using the 5 item scores as observed variables were acceptable (comparative fit index [CFI] and Tucker-Lewis index [TLI]>0.99; root mean square error of approximation [RMSEA]=0.105; χ(2) =70.49, df=5), but the model fit improved after adding the correlation between items 1 and 2 (that assess organized and personal religious activities, respectively) as a sixth observed variable(CFI and TLI>0.99; RMSEA=0.046; χ(2) =14.32, df=4). CONCLUSION: The Chinese version of the DUREL is a reliable and valid measure of religiosity that can be used to assess the relationship of religiosity/spirituality to physical and psychological wellbeing in Chinese respondents. As suggested by other authors, our factor analysis results indicate that the overall score is the best measure derived from the scale, not the three dimensional scores recommended by the original authors.