Factor structure of the General Health Questionnaire (GHQ-12) in subjects who had suffered from the 2004 Niigata-Chuetsu Earthquake in Japan: a community-based study

Toyabe, Shin-ichi; Shioiri, Toshiki; Kobayashi, Kuriko; Kuwabara, Hideki; Koizumi, Masataka; Endo, Taro; Ito, Miki; Honma, Hiroko; Fukushima, Noboru; Someya, Toshiyuki; Akazawa, Kouhei

We performed confirmatory factor analysis in order to find the most fitted model. Confirmatory factor analysis was conducted using AMOS 7 (SPSS Japan Inc., Tokyo, Japan) to test the fits of various models [20] . The candidate models were constructed on the basis of models used in previous studies and those that we found by exploratory factor analysis [5, 7, 16, [21] [22] [23] [24] [25] . Goodness-of-fit of the models was tested by using normal fit index (NFI), Tucker-Lewis coefficient (TLI), comparative fit index (CFI), root mean square error of approximation (RMSEA), Akaike information index (AIC), estimated population discrepancy (F0) and expected cross validation index (ECVI) [3, 4, 26] . Internal consistency of series of items belonging to each factor was evaluated using Cronbach's alpha score [27] . If Cronbach's alpha score of a factor was more than 0.7, we considered internal consistency of the factor to be satisfactory. In that case, we calculated lower scale points for each factor by averaging scales of all items belonging to the factor.