Data Cart

Your data extract

0 variables
0 samples
View Cart
Duration of functionally limiting intellectual disability: Years

Codes and Frequencies

Can't find the category you are looking for? Try the Detailed codes


For sample adults age 18+ who have at least one functional activity limitation (FLANY), and for whom a mental retardation was reported as a condition causing any functional activity limitation (FLRET), FLRETY reports the duration, in years, of the mental retardation.

Data on the duration of limiting mental retardation were collected via the question, "How long have you had [a mental retardation]?" 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, FLRETTP (which specifies the time unit) and FLRETNO (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 (FLRETY) and groups of months (FLRETMO).


FLRETY is completely comparable for 2002-2010.

Beginning in 2011, the phrase "mental retardation" was replaced with the phrase "intellectual disability, also known as mental retardation" in the survey question associated with FLRETY. Apart from this change in wording, the variable is completely comparable for 2002 forward.

Additionally, there is a change in the coding of "unknown" cases for FLRETY, beginning in 2002.


In 2002 forward, the unknowns were categorized as:

  • Unknown number of years (IPUMS NHIS code 96)
  • Unknown-refused (IHIS code 97)
  • Unknown-not ascertained (IHIS code 98)
  • Unknown-don't know (IHIS code 99)

However, in 1997-2001, the category of "Unknown number of years" did not occur.

Analysts can achieve comparability across all years by combining codes for values of 96 and above into a single "unknown" category.


  • 1997-2013; 2014 2015 2016 2017 2018: Sample adults age 18+ who have difficulty with activities due to intellectual disability, also known as mental retardation.


  • 1997-2018