You were close but your generate (gen) statement wasn't quite right.
. bysort year state county: gen employdiff = employment - employment[_n - 1]
(2 missing values generated)
. l, noobs
+---------------------------------------------+
| year state county employ~ employ~f |
|---------------------------------------------|
| 1 1 1 10 . |
| 1 1 1 15 5 |
| 2 2 1 20 . |
| 2 2 1 30 10 |
+---------------------------------------------+
Eric
>Hi I wasn't able to find anything on the archives adressing this issue.
>
>My data is structured as follows
>
>year state county employment
>1 1 1 10
>2 1 1 20
>1 2 1 15
>2 2 1 30
>...
>for 6 years, 50 states, and some counties in each state. I have 1.5 million observations.
>
>I want to construct a variable that is the difference in employment by year in each state and county.
>
>I tried
>
>by year state county, sort: gen newvar = employment-employment[_n-1] but that didn't work.
>
>Any suggestions?
>Thank you!
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Eric G. Wruck
Econalytics
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