Codes and Frequencies
For sample adults age 18+ who have at least one functional activity limitation (FLANY), and for whom a blood problem was reported as a condition causing any functional activity limitation (FLBLOOD), FLBLOODMO reports the duration, in months, of the blood problem.
Data on the duration of a limiting blood problem were collected via the question, "How long have you had [a blood problem]?" Respondents could answer this open-ended question using the time unit of their choice (i.e., days, weeks, months, years, or since birth). The original responses to the question are reported in two complementary variables, FLBLOODTP (which specifies the time unit) and FLBLOODNO (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 (FLBLOODY) and groups of months (FLBLOODMO).
The 1997 forward NHIS Survey Descriptions caution that because the ad hoc classified condition categories (such as a "blood problem" (FLBLOOD)) were not included on flashcards given to respondents during the course of the interview, it is possible that weighted frequencies for these conditions may be underestimated. Thus, the NCHS recommends that "these variables should be analyzed with care."
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: Sample adults age 18+ who have difficulty with activities due to blood or blood-forming organ problem.
- 1997-2018 : SAMPWEIGHT