What does the SCL-90-R really measure? Factorial structure in a mixed sample of undergraduates and patients

The Symptom Checklist-90-R (SCL-90-R, Derogatis, 1983, 2002) is meant to measure nine specific psychopathological dimensions (e.g., somatization, depression) and also provides three global psychopathological indices. However, a large number of exploratory and confirmatory factor analyses have failed to validate their dimensional structure. One possible reason for this could be an insufficient variability in the samples used. To check this effect, a factor analysis of the SCL 90 R was carried out in a combined sample of undergraduates and patients. The nine dimensions identified only matched or approached the original ones in name. Indeed, in most cases there was a poor match among items corresponding to dimensions with identical or similar names. It is concluded, on one hand, that the failure to replicate the factorial structure of the SCL 90 R could be largely explained by the complex logic-semantic structure of the questionnaire; and, on the other hand, that it is highly questionable to interpret the nine SCL 90 R dimensions for any clinical purpose. Thus, it is more advisable to use the instrument as a measure of general emotional distress or psychopathology.