In the 2018 SIPP, children aged 1 to 14 are asked the survey questions via a proxy adult respondent. However, infants (defined as household members less than one year old as of December of the calendar year) do not receive proxy interviews. For most of the variables for health-care utilization and medical expenditures, infants have their variable values set to "not in universe".

In the 2018 data, we identified a processing error causing infants to remain in universe for some of these medical utilization variables. Instead of being set to "not in universe," they received imputed values. The table below provides a brief description of each of these variables along with the number of cases affected.

If data users wish to correct these universes within their analyses, they can do so using the monthly age variable (TAGE_EHC) corresponding to month 12. For example, if TAGE_EHC(month 12)=0, then users should reset variable values to .N, and reset allocation flag values to 0.