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Duration of limiting second unclassified adult problem: Months

Codes and Frequencies

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CLIMANEC2MO reports the duration, in months, of a limiting, "not elsewhere classified," condition. This information is reported only for persons age 18+ who had at least one activity limitation (LANY), and who identified a second problem, not listed on the interviewer-provided flashcard and not one of the other categories available to interviewers for purposes of classifying conditions, as a cause of any activity limitation.

Data on the duration of the limiting condition were collected via the question, "How long [have/has] [you/person] had [condition]?" Respondents could answer this open-ended question using the time unit of their choice (i.e., days, weeks, months, or years). The original responses to the question are reported in two complementary variables, CLIMANEC2TP (which specifies the time unit) and CLIMANEC2NO (which reports the number of such units). For the NHIS public use files, the National Center for Health Statistics (NCHS) recoded the results from these two variables to create two other variables using standard time units: years (CLIMANEC2Y) and groups of months (CLIMANEC2MO).


Apart from a change in the coding of "unknown" cases, this variable is comparable across years.


All "unknown" cases for this variable share a common first digit of "9." The meaning of the second digit following the 9 differs for 2001 versus 2002 forward. In the earlier period, the "unknowns" were categorized as:

  • Unknown number of days (IPUMS NHIS code 91)
  • Unknown number of weeks (IHIS code 92)
  • Unknown number of months (IHIS code 93)
  • Unknown number of years (IHIS code 94)
  • Unknown time with condition (IHIS code 95)

In the latter period, "unknowns" were categorized as:

  • Unknown-refused (IHIS code 97)
  • Unknown-not ascertained (IHIS code 98)
  • Unknown-don't know (IHIS code 99)

Analysts can achieve comparability across all years by combining codes with a common first digit of 9 into a single "unknown" category.


  • 1997-2013; 2014 2015 2016 2017 2018: Persons age 18+ limited due to second unclassified impairment or problem.


  • 1997-2018