Data and Documentation Issues

This page is updated as necessary with any known issues related to the HILDA data or its documentation.

Release 24

Mother’s location at birth

Four family background W24 variables (xfmlbbd, xfmlbdt, xfmlbbdy, xfmlbdty) are incorrect. Records coded as -1 (Not asked) were incorrectly recoded to 9999 (Overseas).

To fix the derived variables (xfmlbbd/xfmlbdt), 9999 should only be retained for new entrants born in Australia. For all other respondents, 9999 should be recoded to -1 (Not asked).

To fix the history variables (xfmlbbdy/xfmlbdty), Wave 24 data corrected as above should be merged with Wave 23 data. Continuing respondents should inherit their Wave 23 value, while new entrants should use the corrected Wave 24 derived value.

Here is a sample code in SAS to fix the variables xfmlbbd and xfmlbbdy in the general release rperson file:

/* Fix for derived variable xfmlbbd */
data rperson_24;
set r24.rperson_x240c;
if xhhpq=1 then xfmlbbd=-1;
else if xhhpq=2 and xancobn=1101 and xfmlbbd=9999 then xfmlbbd=9999;
else if xhhpq=2 and xancobn ne 1101 and xfmlbbd=9999 then xfmlbbd=-1;
run;
proc sort; by xwaveid; quit;

/* Fix for history variable xfmlbbdy */
data rperson_23;
set r24.rperson_w240c;
run;
proc sort; by xwaveid; quit;

data rperson_24;
merge rperson_24 (in=x) rperson_23;
by xwaveid;
if x;
if xhhpq=1 and xfmlbbdy=9999 then xfmlbbdy=wfmlbbdy;
else if xhhpq=2 then xfmlbbdy=xfmlbbd;
run;

The corrected variables will be available in Release 25.

Twin Identifiers

An issue was identified in the code that generates the twin identifier variables _hhtwxid and _hhtwid, which was incorrectly hard-coded to Wave 18. As a result, twins first identified from Wave 19 onwards were excluded from these derived variables. However, twin status can be derived from the household data, with twins defined as full siblings who share the same birthdate (or have birthdates one day apart). Triplets and other multiple births are not classified as twins.

The corrected variables will be available in Release 25.

Income band

The variables whiband4 and xhiband4 were erroneously recoded. Specifically, values of 9 were recoded to -3, and values of 8 were recoded to -4.

The corrected variables will be available in Release 25.

Issues in previous releases