A comparative investigation of the principal component structure of the 28 item version of the General Health Questionnaire (GHQ). 15-year-old schoolgirls in England, Greece, Turkey and West Germany.

The 28-item version of the General Health Questionnaire of 15-year-old schoolgirls obtained under identical conditions in two separate studies was subjected to principal component analysis (PCA). Varimax rotation produced different numbers of components for the different groups, but restricting the number of components to be rotated to four produced similar component structures, as supported by the coefficient of factor similarity, for both Turkish and Greek groups in their home countries and a heterogeneous non-British group in London in comparison to British girls. Different structures were obtained in schoolgirls from Greece, in Munich, and from the Indian subcontinent in London. Analysis of variance of the factor scores of a combined PCA produced significant overall group differences for all components and specific group differences for anxiety and insomnia, social dysfunction, and severe depression. Somatic symptoms and anxiety and insomnia subscales, either alone or in combination with other subscales, contributed most frequently to morbidity.