The scale was developed by Deragotis (1977, 1994; as cited in Dağ, 1991; 2000) and its validity and reliability studies in Turkey were conducted by Dağ (1991). The scale, which is a psychiatric screening tool to measure psychological and physical symptoms and the level of the strain or negative stress reaction experienced by the individual, consists of 90 items based on a 5-point Likert-type assessment (none/very little/moderately/very much/extremely) and is based on self-report. The scale has 9 subscales reflecting 9 different symptom groups: Somatization, Obsessive-Compulsive, Interpersonal Sensitivity, Depression, Anxiety, Hostility, Phobic Anxiety, Paranoid Ideation and Psychoticism. The scale also has three indices, namely General Symptom Index (GSI), Positive Symptom Total (PST) and Positive Symptom Index (PSDI), and an additional scale consisting of items assessing feelings of guilt, eating problems and sleep-related problems. Studies on the original and Turkish versions of the scale indicate that the scale is valid and reliable. The scale has been used in many studies in Turkey.
As a cut-off score, many studies have been conducted. In İhsan Dağ's study, the GSI was 1.06 / Kılıç (1987) GSI was 0.91 / Çuhadaroğlu (1985) GSI was 0.85 / Fidaner & Fidaner (1984) GSI was 0.95 / Degoratisin (1977) in the USA, the average GSI in adult psychiatric outpatients was 1.26 and in adult normals the GSI was 0.31. Almost all studies in Turkey were conducted with normal groups of university students. Only Çuhadaroğlu's study in 1986 used 100 adolescents referred to a university health center for psychiatric examination, and the mean GSI in this study was 1.28. In İhsan Dağ's 1991 article (p. 10), he states that "for university students, a GSI score of 1.00 GSI score can be taken as a basis, 1.57, which is 1 standard deviation above this value, can be considered as the lower cut-off points for recognizing subjects with "mild psychological symptoms" and 2.14 GSI score, which is 2 standard deviations above this value, can be considered as the lower cut-off points for recognizing subjects with "psychological symptoms"."
* Reference: Dr.Psk İhsan DAĞ; "Reliability and Validity of the Symptom Screening List (SCL-90-R) for University Students"; Turkish Journal of Psychiatry 2: (1) 1991