Hello, I’m working with CPS data, looking at earnings. I need data for Sept 2023 and 2021, and when I filter by those dates, I get the outgoing rotation groups (earner study). However, once I look into earnweek2, I get a median of $1 million.
I know this isn’t accurate, so why would this be the result? Any help is appreciated!
From my experience, a common mistake with using IPUMS income variables is forgetting to account for NIU (not in universe) specialty coding. Let me describe what these specialty codes are and how you can obtain your estimates with them in mind.
Weekly earnings are not ascertained for all persons in the CPS. For example, respondents are not asked to report weekly earnings for infants, toddlers, or young children. The criteria used to determine whether someone is eligible to have data for a variable is the variable’s universe. Not in universe specialty codes are assigned in cases when a respondent is outside of the variable’s universe. For example, infants are by default assigned the NIU code for weekly earnings. The codes tab in the documentation for EARNWEEK2 notes the following specific variable code:
999999.99 = N.I.U.
The universe for EARNWEEK2 is provided in the its universe tab:
1989+ (non-ASEC): Civilians 15+ currently employed as wage/salary workers and in 2 (out of 8) rotation groups. Excludes self-employed persons.
NIU observations are typically excluded in analyses. However, it is important to be aware of who is then excluded from your estimates. The median value of EARNWEEK2 with NIU observations excluded will report the median weekly earnings of non self-employed civilians 15+ currently employed as wage/salary workers.
IPUMS CPS offers an Online Analysis Tool that can help you run these types of tabulations. In the screenshot below, I have selected to analyze all BMS samples and chosen the Means program. I applied the selection filters year(2021, 2023), month(9), earnweek2(0-999999) in order to restrict the analysis to in-universe values of EARNWEEK2 for September 2021 and 2023. I entered EARNWEEK2 into the dependent field and YEAR into the row field. I also selected EARNWT as my sampling weight (since EARNWEEK2 is one of the earner study variables) and requested that the median be displayed in the Median/Percentile Options submenu. The results showed a median weekly income of $920 in 2021 and $1000 in 2023.
