For persons eligible for the self-administered questionnaire (SAQELIG), K6SUM is the summed scale value measuring nonspecific psychological distress over a 30-day recall period. This scale, developed by Ronald C. Kessler and known as the Kessler 6 Scale (K6), asks about six manifestations of nonspecific psychological distress.
Kessler recommends scoring the scale by assigning 0 to 4 points for each of the six questions, based on the reported frequency of the feelings (i.e., 0 for "none of the time"; 1 for "a little of the time"; 2 for "some of the time"; 3 for "most of the time"; and 4 for "all of the time"). The range for summed responses on the K6 Scale is thus 0 to 24, with 0 suggesting the lowest level of nonspecific psychological distress, and 24 suggesting the highest level of nonspecific psychological distress. According to the scoring criteria proposed by Kessler, persons with a score of 13 or greater are likely to be experiencing severe mental illness.
Kessler's instrument asks how often, during the past 30 days, the respondent felt:
- So sad that nothing could cheer you up? (ASAD)
- Nervous? (ANERVOUS)
- Restless or fidgety? (ARESTLESS)
- Hopeless? (AHOPELESS)
- That everything was an effort? (AEFFORT)
- Worthless? (AWORTHLESS)
As noted above, acceptable responses fell into five categories, ranging from "none of the time" to "all of the time."
K6SUM is a count variable with values ranging from 0 to 24. Missing data codes are specified below.
98: Unknown - not ascertained
- 2004-2019: Adults aged 18 and older.
- 2004-2020: Adults aged 18 and older.
- 2004-2020 : SAQWEIGHT