IPUMS FAQs: How do I link basic monthly samples with the ASEC sample?

At IPUMS we try to address every user’s questions and suggestions about our data. It is just one feature that adds value to IPUMS data. Over time, many questions are often repeated. In this blog series, we will be sharing some of these frequently asked questions. Maybe you’ll learn something, or perhaps you’ll just find these interesting. Regardless, we hope you enjoy.

Here’s one of those questions:

How do I link basic monthly samples with the ASEC sample?

The CPS has a more complicated sampling design than most national surveys. Households that are selected to be a part of the CPS are first included for four consecutive months, then intentionally excluded for eight months, then finally included for four additional months. The sampling design opens up the possibility for the CPS to be used as a panel. One challenge in this has to do with the ASEC, or what is sometimes called the “March Supplement.” The ASEC is arguably the most popular part of the CPS, but includes several complicating features. In particular, the ASEC is larger than other basic monthly samples and includes individuals from months other than those in the March basic monthly sample. Due to this feature, it is not possible to simply link respondents in the ASEC with other basic monthly samples with the CPS person ID variable CPSIDP.

Instead, using the ASEC while taking advantage of the panel structure of the CPS requires a more detailed linking variable. The IPUMS CPS Team developed the variable MARBASECIDP for just this purpose. This variable represents a sizable reduction in the burden on users to link the ASEC to other basic monthly samples and unlocks the potential for many previously unexplored research questions.

More information about linking basic monthly samples with the ASEC sample can be found in this working paper by Flood and Pacas.

Story by Jeff R. Bloem
PhD Student, Department of Applied Economics
Graduate Research Assistant, Minnesota Population Center