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Re: st: [merging US industry level data]


From   Philipp Rehm <Philipp.Rehm@gmx.de>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: [merging US industry level data]
Date   Fri, 29 Sep 2006 14:41:16 +0200

You don't give a whole lot of information about your data-set, but there are a few things that can be said.

1) You need to generate the same industry level variable in both data-sets, i.e. you need to generate a 3-digit level industry code inside the data-set with the 4-level data-set (let's call this data-set the 'master' data-set).
It is not clear how the 4-digit and the 3-digit industry variables relate to each other, but let's assume that you can simply cut off the last digit of the 4-digit variable to derive the 3-digit variable (e.g., codes 1230 to 1239 at the 4-digit level correspond with code 123 at the 3-digit level.

Assuming this, as well as that your 4-digit level industry variable is coded in integers (and called industry_4d), you could get the 3-digit level variable with something like this:

gen int industry_3d = real(substr(string(industry_4d),1,3))

In your other data-set, you also need to have a variable that is called "industry_3d" (and you need to make sure that it is equivalently coded, of course - which I assumed above).

2) Depending on what type of merge you want to do, you probably need to sort both data-sets by the identifier variables (the variables you want to merge on). Assuming you want to merge on, say, "year" and "industry_3d", you would need to sort both data-sets by "year industry_3d."

3) The you can merge, along the following lines:
use master.dta, clear
merge year industry_3d using using.dta

(where the data-set with the original 3-digit level industry level variable is called "using.dta").

HTH,
Philipp

Rohit wrote:

hi there,
mine is a very preliminary question. i am working with the US industry level
data and i want to merge the variables of 4-digit level industries to 3-digit
and also create a variable for 3-digit.
could anybody help me with that?
thanks
rohit
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