Single adult or multiple adults per househould in the Adult Sample File since 1997?


The NHIS Sample Design User Note on the IHIS website states that: One feature of the 1997 survey redesign “merits emphasis: the random selection of a single adult and a single child to answer a battery of additional questions.” So this means that, for any sampled household, there should be only ONE member of the household in the sample adult file, correct? However, for few households I have found that that this is not the case. For example, I see that there are observations with the same value of SERIAL (and YEAR) but with non-missing information about variables from the sample adult file. This happens in only relatively few cases but again I wonder if I am missing something here.


I have confirmed that around 2.5% of IHIS households with at least one sample adult actually have multiple sample adults. This is due to the fact that sample adults are chosen by family, not by household. Since multiple families can reside in a single household, multiple sample adults can be chosen from a single household. Note that the number of sample adults in a household is always less than or equal to FAMNUMTOT.

Hope this helps.