# best use of occ1990 for year-by-year stats in the CPS data? **URL:** \ **Category:** CPS\ **Created:** [September 4, 2015, 12:10am UTC](https://forum.ipums.org/t/best-use-of-occ1990-for-year-by-year-stats-in-the-cps-data/1021 "2015-09-04T00:10:00Z")\ **Posts on this page:** 2\ **Page:** 1
**Author:** ![michelg](https://avatars.discourse-cdn.com/v4/letter/m/9f8e36/32.png) [@michelg](https://forum.ipums.org/u/michelg)\ **Post date:** [September 4, 2015, 12:10am UTC](https://forum.ipums.org/t/best-use-of-occ1990-for-year-by-year-stats-in-the-cps-data/1021/1 "2015-09-04T00:10:00Z")
I’m looking at within-occupation changes over time in the CPS, and it seems like occ1990 is the variable to use. I’m confused, though, since I still see some noticeable noticeable breaks in trend around the year when the census occupation definitions changed. For example, if I calculate percent change in employment for each occupation, I see a noticeable jump in 2003, when the 2000 definitions kicked in. Is there a recommended way to use occ1990 in order to get smooth within-occupation trends, or is this jump just an artifact of all the recoding? Thanks! ---
**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:** [September 9, 2015, 4:01pm UTC](https://forum.ipums.org/t/best-use-of-occ1990-for-year-by-year-stats-in-the-cps-data/1021/2 "2015-09-09T16:01:00Z")
The Census Bureau significantly changing their [occupational coding scheme](https://cps.ipums.org/cps-action/variables/OCC#codes_section) in 2003 is the likely cause of the breaks in trend you are seeing. OCC1990 is our [best effort](https://cps.ipums.org/cps-action/variables/OCC1990#description_section) to maintain a consistent coding scheme across time; however, these major shifts in classification can still cause inconsistencies such as you have discovered. I am sorry that I do not have better news to deliver.