In addition, gender differences were assessed by a depression-subscale of the Health and Daily Living Form in the Panel Study of Belgian Households [11-13], and the Symptom Checklist 90-Revised in the Belgian Health selleck chemical Interview Surveys of 2001 and 2004 [14,15]. Although this recurrent epidemiological finding indicates the existence of a true gender difference in the prevalence of depression in Belgium and abroad, the possibility remains that the observed difference between men and women is partly due to possible measurement variance. In the present study, we aim to evaluate the measurement invariance of a depression scale as a tool for making cross-gender comparisons. Our estimates of gender differences in depression in the general Belgian population will therefore reflect true differences between men and women, rather than being contaminated by possible group-specific attributes unrelated to depression.
In the present study, we made use of the Belgian sample of the third round of the European Social Survey (ESS 3) [16], organised in 2006 and 2007. Depression is assessed by the Center for Epidemiologic Studies – Depression Scale or CES-D [17]. Previous studies on the measurement equivalence of the 20-item CES-D scale are ambivalent, with several studies pointing towards a gender bias [18-22] while other studies suggest measurement equivalence of the scale across gender groups [23,24]. Several other measurement inventories for depression also pointed towards a gender bias [5,13,25,26]. In the ESS 3, depression was not assessed using the CES-D 20, but respondents were administered an 8-item version of the CES-D.
While the CES-D 20 is used extensively in international research, the CES-D 8 has seldom been used before. Measurement equivalence and factorial invariance When depression is measured using a multi-item self-report instrument such as the CES-D, each item is considered an imperfect measure of one of the symptoms of depression, but as a whole, the set of items is hoped to provide a valid indirect assessment of a latent construct called depression. When the items are summed Brefeldin_A to form a composite measure, it is also assumed that the total measurement score will be more reliable than single item scores [27]. Measurement equivalence or invariance is the condition that is attained when individuals with equivalent true scores on a measurement instrument for a latent construct have the same probability of a particular observed score on an associated test [28]. Measurement equivalence or invariance is the broader concept that subsumes factorial invariance. The latter is a measurement equivalence approximation that can be tested with confirmatory factor analysis (CFA), a special case of structural equation modelling.