Thanks, Nick. I looked into the suggestions and I think I might have
confused you on my problem. My panel data is like this:
Gvkey psic ssic year subno
1223 4767 4743 1999 1
1223 4767 4763 1999 2
1223 4757 4767 1999 3
1223 4767 4753 1999 4
1223 4777 4787 1999 5
1223 4767 4743 1999 6
Using command unique, I can count the distinct values of psic and ssic by
gvkey by year. So for psic it's 3 and for ssic it's 5. what I want is to
count the distinct values of both psic and ssic by gvkey by year. In this
case, it's 7 (4767, 4757, 4777, 4743, 4763, 4753, 4787). How to generate a
new variable for my purpose? Hope I'm clear now. Pls help.
Thanks.
Wanli Zhao
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Nick Cox
Sent: Saturday, June 18, 2005 11:52 AM
To: [email protected]
Subject: st: RE: RE: unique value count in several variables
By "unique" here I think you mean "distinct".
Try -groups- from SSC. Or -egen, group()- and then tabulate.
Nick
[email protected]
Wanli Zhao
> I have a simple question but got stuck on a simple solution.
> I have a panel
> and let's say cross-section id is gvkey and time id is year.
> There are two
> variables, say, primary sic and secondary sic. My aim to count the
> unique value of sic in both variables by gvkey by year. I know the
> 'by' thing is straightforward but is there a quick solution to count
> the unique observation in both variables? I know the commands such as
> unique, distinct and egenmore nvals. They work perfect for a single
> variable.
> Also, on the
> webpage there is a explanation of the unique combination of two
> variables and how to count that. I guess mine is different. Your help
> is appreciated.
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