MTUS: own children in household?

I am using the MTUS-X files to get comparable estimates across US data (1975, 1998, 2003-2018), rather than using AHTUS-X and ATUS-X.

The variable for “number of children under 18” (NCHILD) states that it may not be limited to own children. However, I am interested in constructing a sample of mothers with an own household child.

Is it possible to use the US MTUS data to discern whether these children are own children? Or, is it possible to use the AHTUS data for 1975 and 1998 to find out whether UNDER18 refers to an own child? This does seem to be possible using ATUS-X for years 2003-2018 (KIDUND18), but I am not sure if that variable is available in earlier years.

Thank you very much!

Unfortunately, the available information used to generate NCHILD in MTUS does not allow for a distinction of own children. Additionally, the child identifier variables in AHTUS may not necessarily only identify own children, and also could identify any child living within the household. With that said, as you point out, strictly identifying own children, for years 2003-2018, is a nice feature of the ATUS data (see here).

Similar to your previous question, it seems there are two possible ways to proceed. The first approach is to merge the MTUS data onto the ATUS and AHTUS data. You can match on CASEID in ATUS and PERSID in MTUS, when the data are restricted to respondents only. You can match on IDENT and SAMPLE, which are available in both MTUS and AHTUS. The second approach is to just use the information in the ATUS and AHTUS files, if you do not need any additional information from the MTUS files.

Thank you very much, Jeff, for the answer to both my questions – I appreciate it!