# Discrepancy between last year and last week self-employed CPS March Supplement

**URL:** <https://forum.ipums.org/t/discrepancy-between-last-year-and-last-week-self-employed-cps-march-supplement/1002>\
**Category:** CPS\
**Created:** [August 17, 2015, 3:16pm UTC](https://forum.ipums.org/t/discrepancy-between-last-year-and-last-week-self-employed-cps-march-supplement/1002 "2015-08-17T15:16:00Z")\
**Posts on this page:** 3\
**Page:** 1

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**Author:** ![robcdent](https://avatars.discourse-cdn.com/v4/letter/r/ac91a4/32.png) [@robcdent](https://forum.ipums.org/u/robcdent)\
**Post date:** [August 17, 2015, 3:16pm UTC](https://forum.ipums.org/t/discrepancy-between-last-year-and-last-week-self-employed-cps-march-supplement/1002/1 "2015-08-17T15:16:00Z")

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I’m using the CPS March Supplement via IPUMS to calculate the number of self-employed workers by year. Using the class of worker last year question (classwly), unincorported self-employed workers drop from ~10 million to ~8 million for 1996-1997 while incorporated self-employed jump from ~4 million to ~6 million (see figure below).

I’m defining incorporated self-employed as classwly==(14) and unincorporated as classly==(10,13). From what I’ve read, these definitions don’t change in 1996-97 and neither does the weight variable (wtsupp). Is there a coding mistake where some of the unincorporated are being assigned as incorporated? Thanks so much for your help!

 ![questionImage-1-17101424-full.png](https://us1.discourse-cdn.com/flex019/uploads/ipums/original/1X/8f06d832cba3ed67e1a958eb94fcc293b46466f0.png)

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**Author:** ![Tim\_Moreland](https://avatars.discourse-cdn.com/v4/letter/t/f1d935/32.png) [@Tim\_Moreland](https://forum.ipums.org/u/Tim_Moreland)\
**Post date:** [August 18, 2015, 4:36pm UTC](https://forum.ipums.org/t/discrepancy-between-last-year-and-last-week-self-employed-cps-march-supplement/1002/2 "2015-08-18T16:36:00Z")

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I was able to replicate your issue with both IPUMS-CPS data and with the [CPS files](http://www.nber.org/data/current-population-survey-data.html) released by the Census Bureau. Generally, IPUMS-CPS tries to maintain as close of a relationship with the original data as possible, which means that errors in the source data are also likely to be reflected in the IPUMS-CPS data. Since the values for [CLASSWLY](https://cps.ipums.org/cps-action/variables/CLASSWLY#codes_section) come directly from the original CPS files, I recommend that you try contacting the [Census Bureau](http://www.census.gov/cps/contact/) for further information.

Sorry that I could not be of more direct assistance.

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**Author:** ![Johannes\_Mueller](https://avatars.discourse-cdn.com/v4/letter/j/ed655f/32.png) [@Johannes\_Mueller](https://forum.ipums.org/u/Johannes_Mueller)\
**Post date:** [May 7, 2019, 5:17pm UTC](https://forum.ipums.org/t/discrepancy-between-last-year-and-last-week-self-employed-cps-march-supplement/1002/3 "2019-05-07T17:17:03Z")

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I am very late to the question, FFR, Levine 2017 QJE “Smart and Illicit: Who Becomes an Entrepreneur and Do They Earn More” report that the definition changed over time.