Internal structure of the scale
The first task was to demonstrate that the final 15-item scale meets the planned conceptual framework. This was illustrated by the results of the factorial analyses of the data of the normative sample survey in Italy. A stratified population sample was drawn from four geographical regions of Italy and five age groups to get a regionally representative population sample. The raw questionnaire was submitted to about 250 sampled women by interviewers who asked the women to complete the questionnaire themselves, and 230 women were available for analysis. The study was executed in spring/summer 2005.
Five, theoretically independent dimensions (domains), as identified in the conceptual framework were confirmed by the factorial analysis: ‘sexual problems [SEX]’, ‘menstrual problems [MENS]’, ‘hormonal effects [HORM]’, ‘psychological problems [PSYCH], and ‘abdominal complaints [ABDOM]’. The factor solution for the 15-tem scale explained 66.1% of the total variance in the database, which is considered as good result.
The items belonging to each of the five domains seem reasonable from biological understanding and basically confirm the conceptional framework.
In addition to the Italian normative survey, the results were re-confirmed with data of the German validation survey (108 German women aged 25-60 years of age were available for analysis): The German factorial analysis showed very similar results as the Italian one: A slightly higher percentage of the total variance was explained by the five domains in the German sample (73.3% and 66.1% in the German and Italian sample, respectively). Again, the same 5 domains were extracted in the factorial analysis and the factor loadings were very similar if not identical with the Italian sample.