Codes and Frequencies
For sample adults, ANERVOUS reports responses to the question, "During the past 30 days, how often did you feel nervous?"
At the beginning of the section of the survey devoted to evaluating nonspecific psychological distress, interviewers stated, "Now I am going to ask you some questions about feelings you may have experienced over the past 30 days." They then handed respondents a flashcard listing five categories (all of the time; most of the time; some of the time; a little of the time; none of the time), from which respondents were to select the appropriate response. The Field Representative's Manuals for 1997-2000 directed the interviewer to "reread the question, emphasizing the wording of the answer categories," if the respondent gave an answer that did not match these categories.
ANERVOUS is one of a series of six variables whose responses can be summed as a scale 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'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."
Kessler recommends scoring the scale by assigning 0 to 4 points for each of these 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.
To assist researchers who intend to sum responses to the variables included in the K6 Scale, IPUMS NHIS assigns codes that are consistent with Kessler's advised scoring system (i.e., with "none of the time" coded as 0 and "all of the time" coded as 4). To produce valid results, users must exclude not in universe cases (persons other than sample adults, code 6 in IHIS) and unknown cases (codes 7, 8, and 9 in IHIS) before summing the responses.
In 2021, a dichotomous variable (PDISTRESSK6) was introduced to record whether a respondent's summed K6 score fell above or below the 13-point threshold for significant psychological distress.
As a follow-up to the K6 Scale questions, the NHIS included a question that was not part of Kessler's original survey instrument. All sample adults who answered "some of the time," "most of the time," or "all of the time" to any of the six questions included in the Kessler 6 Scale were asked, "Altogether, how much did these feelings interfere with your life or activities: a lot, some, a little, or not at all?" (AFEELINT1MO). In 1999, additional follow-up questions collected further information about how "these feelings" affected the person (see FBADHOWOFT, FBADMORE, FBADLESS, FBADUNABLE, and FBADCUTDOWN).
Prior to 2019, this variable is comparable over time. The NHIS questionnaire was substantially redesigned in 2019 to introduce a different data collection structure and new content. For more information on changes in terminology, universes, and data collection methods beginning in 2019, please see the user note.
- 1997-2018: Sample adults age 18+.
- 2021: Sample adults age 18+.
- 1997-2018, 2021
- 1997-2018, 2021 : SAMPWEIGHT