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Duration of functionally limiting intellectual disability: Time period

Codes and Frequencies

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For Sample Adults age 18+ who, without using special equipment, had any difficulty with one or more functional activities (FLANY), and for whom mental retardation was reported as a condition causing a functional activity limitation (FLRET), FLRETTP reports the time unit in which the duration of the mental retardation was measured by the respondent.

Data on the duration of the limiting mental retardation were collected via the question, "How long have you had [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, as noted above, 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).


FLRETTP is completely comparable for 1997-2010.

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 FLRETTP. Apart from this change in wording, the variable is completely comparable for 1997 forward.


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


  • 1997-2018