‘ASPOUSE’ is a pointer variable to identify the person’s spouse in the same household. It gives the line number (LINENO) of the spouse if the person has, otherwise 0 meaning that “no spouse of this person present in household”. (https://cps.ipums.org/cps-action/variables/ASPOUSE#description_section)
However, when I worked on the CPS data from 2003-2018, there was a suspicious undocumented value ‘-1’ emerges. I produced a contingency table with the CPS survey year. Here it is.
As the table shows, the value ‘-1’ only appears before 2007 and at the same time there is no ‘0’ before 2007. I don’t exactly know what happened but I’m guessing that from 2003-2006, ‘-1’ represents ‘no spouse of this person present in household’ instead of ‘0’. It might be that the Census Bureau or IPUMS forgot to document this change.
Another evidence that supports my hypothesis is that, in the IPUMS-ATUS dataset, ‘ASPOUSE’ is only available 2007-2018. That implies that this variable has some important change in and after 2007.
Hope it make sense and anyone familiar with this variable could address my concern. Thanks!