# CPS-ATUS merge dropping a large number of observations

**URL:** <https://forum.ipums.org/t/cps-atus-merge-dropping-a-large-number-of-observations/5295>\
**Category:** CPS\
**Created:** [May 23, 2023, 4:35pm UTC](https://forum.ipums.org/t/cps-atus-merge-dropping-a-large-number-of-observations/5295 "2023-05-23T16:35:39Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Vedika\_Nair](https://avatars.discourse-cdn.com/v4/letter/v/9de053/32.png) [@Vedika\_Nair](https://forum.ipums.org/u/Vedika_Nair)\
**Post date:** [May 23, 2023, 4:35pm UTC](https://forum.ipums.org/t/cps-atus-merge-dropping-a-large-number-of-observations/5295/1 "2023-05-23T16:35:39Z")

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I am trying to merge CPS data to ATUS data for years 2003-2019. As mentioned in [this](https://www.youtube.com/watch?v=6RW9T9I5zZ0) workshop, I first dropped all observations that weren’t MIS 8 and then merged to ATUS using CPSIDP (1:1 merge). However, only 16,773 (out of 651749) observations merged. Should I be able to merge more observations? If yes, how?

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**Author:** ![KariWilliams](https://avatars.discourse-cdn.com/v4/letter/k/82dd89/32.png) [@KariWilliams](https://forum.ipums.org/u/KariWilliams)\
**Post date:** [May 26, 2023, 6:54pm UTC](https://forum.ipums.org/t/cps-atus-merge-dropping-a-large-number-of-observations/5295/2 "2023-05-26T18:54:13Z")

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Could you please clarify which CPS samples you are using? If you are only using ASEC data, your month-in-sample restriction criteria are too narrow; for within-year ASEC to ATUS links you can retain individuals with IPUMS CPS MISH values of 5-8 without repeat observations of the same individual. However, if you are using basic monthly data, restricting to a single MISH value (e.g., the eight household interview) is appropriate. Without knowing which CPS samples you are using, it is harder to comment on the number of cases you are merging. However, I will note that I would not expect all cases to match as only a subsample of outgoing CPS households are selected for inclusion in the ATUS sample; you can see [sample sizes from IPUMS ATUS](https://www.atusdata.org/atus/sample_summary.shtml) and review Chapter 3 of the [BLS ATUS User’s Guide](https://www.atusdata.org/atus/resources/linked_docs/atususersguide.pdf) for more details on sample size and strata, as well as information on response rates.