This mixed population was chosen because of the nature of the instrument. The STAI principally measures anxiety as a feature of the general population, so the main study sample to test the properties of the instrument should be 'healthy normal subjects'. However it is also important to test the properties of the instrument in a population that manifests higher than normal levels of anxiety. Depressed patients were chosen on the basis that this patients population was easier for the researchers to recruit taking into consideration practical issues.
Patients were physically healthy with normal clinical and laboratory findings (Electroencephalogram, blood and biochemical testing, thyroid function, test for pregnancy, B12 and folic acid). They came from the inpatient and outpatient unit of the 3rd Department of Psychiatry, Aristotle University of Thessaloniki, General Hospital AHEPA, Thessaloniki, Greece. They were consecutive cases and were chosen because they fulfilled the above criteria.
The normal controls group was composed by members of the hospital staff, students and other volunteers. A clinical interview confirmed that they did not suffer from any mental disorder and their prior history was free from mental and thyroid disorder. They were free of any medication for at least two weeks and were physically healthy.
All patients and controls provided written informed consent before participating in the study.
The Greek translation along with the translated manual of the test will be available from the same publisher of the English version of the test and manual.
In 20 of the patients the instrument was re-applied 1–2 days later