Linking parents to age of each child in NHIS

HEALTH SURVEYS
1

Hello,

For each adult who is a parent in NHIS, I am aiming to count how many children they have who are 4-years-old. Based on this guide, I believe I can follow the provided guidance on “count the number of own children under the age of 10” using momloc and poploc

  1. Are there any limitations or differences in applying this approach to NHIS?
  2. I also saw I could “attach characteristics” for mom and dad, e.g. NHISPID - would there be any reason to approach it this way rather than following the code in the above guide?
  3. And what years will this be available? Am I right in thinking this would be possible from e.g. 2002-2018, but not from 2019 onwards in NHIS given there is no longer a complete roster with the age of all children from 2019 onwards?

I plan to use this with restricted data, where I will ask the RDC to perform a data linkage based survey year, whether the person has a child who is 4-years-old, and a restricted variable (state of residence).
4) My understanding is that this should be doable if I add my derived variable for child_aged_4 to my IPUMS extract before I send it to the RDC?
5) Just to triple check: Am I right in understanding that I cannot access state of residence in any public use files?

Thank you!

2

It’s straightforward to identify parents of 4-year-olds in IPUMS NHIS samples from 1997-2018. You can either use a modified version of the code provided in the IPUMS USA user guide that you referenced, or the attach characteristics tool in the extract engine. Both methods will give you the same results since they utilize the parental links in MOMLOC and POPLOC, though it may be more straightforward to use the code since the tool does not attach the characteristics of children onto the parent records (rather it attaches parental information onto child records). Note that MOMLOC and POPLOC and the attached characteristics feature are based on IPUMS-constructed parent-child links, and identify the child’s biological, step, or adoptive parent in the household. This includes identifying the spouse or unmarried partner (in the case of householder/unmarried partner pairings) of a child’s parent as the child’s other parent.

You are correct that identifying all parents of 4-year-olds is not possible with NHIS data from 2019 and later. The 2019 NHIS redesign restricted data collection to a single randomly selected sample adult (identified with ASTATFLG) and a single sample child (identified with CSTATFLG) per family. In most cases, the sample adult is the parent of the sample child (reported in ISPARENTSC). However, the lack of a full household roster makes it impossible to determine the ages of all children in a household from 2019-onwards. IPUMS NHIS does not offer family interrelationship variables or the attach characteristics feature for 2019-forward NHIS data.

You are correct that the state of residence is not available in the public use files. You may be interested in our user notes on (1) unique identifiers and linking keys in the NHIS and (2) linking IPUMS NHIS data with restricted-use versions from NCHS, which includes sample proposal language to reference. You can use NHISPID, created by IPUMS NHIS by concatenating identifiers in the public use file, to link records between the IPUMS NHIS and public use files. For records from 1997-2018, the identifier is composed of the following components: a prefix (“00”), the four-digit YEAR, the six-digit household number (HHX), the two-digit family number (FMX), and the two-digit person number (PX). Note that in the 2004-2018 samples, PX in IPUMS NHIS is actually called FPX in the NCHS data. From 2019-onwards, NHISPID includes a three-digit prefix (“000”), the four-digit YEAR, an “H” followed by the six-digit household number (HHX), the one-digit person number (PERNUM), and a trailing “0”.

3

Thank you so much for answering all my questions and for this valuable information!

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