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st: Calculating Industry Experience
From
"Lawal, Olusola O" <[email protected]>
To
"'[email protected]'" <[email protected]>
Subject
st: Calculating Industry Experience
Date
Thu, 13 Feb 2014 18:39:31 +0000
I have over 100,000 observations and 200 variables on acquisitions and their directors, but 10
observations and 5 variables will be enough to show the problem.
My data looks like this
dir_id year SIC TargetSIC Acq
--------------------------------------------------
10043 2007 1111 . 0
10043 2007 . 1450 1
10043 2008 1113 . 0
10043 2009 . 1111 1
10043 2010 1111 . 0
13944 2007 1112 . 0
13944 2008 1113 . 0
13944 2009 5760 . 0
13944 2008 1113 . 0
13944 2009 . 5760 1
---------------------------------------------------
I am trying to calculate industry experience based on matching SIC with TargetSIC of the director (dir_id) which is the difference (in years) from a time when Acq = 1 to a time when Acq = 0. In a different format, what I would like to calculate is the variable IndustryExperience below.
dir_id year SIC TargetSIC Acq IndustryExperience
--------------------------------------------------------------------
10043 2007 1111 . 0 .
10043 2007 . 1450 1 .
10043 2008 1113 . 0 .
10043 2009 . 1111 1 1 (2009 (1111 from TargetSIC) - 2007 (1111 from SIC))
10043 2010 1111 . 0 .
13944 2007 1112 . 0 .
13944 2008 1113 . 0 .
13944 2009 5760 . 0 .
13944 2008 1113 . 0 .
13944 2009 . 5760 1 1 (2009 (5760 from TargetSIC) - 2007 (5760 from SIC))
---------------------------------------------------------------------
The problem I have is that I don't know how to attach grab a specific year and make it a reference point for other years within the same dir_id.
I am fairly new to Stata, but I imagine a loop and a global variable would do the trick?
Any suggestions would be greatly appreciated!
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