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Re: st: [...] drop command with several conditions


From   Nick Cox <[email protected]>
To   "[email protected]" <[email protected]>
Subject   Re: st: [...] drop command with several conditions
Date   Sat, 22 Mar 2014 14:06:23 +0000

One way to do this

egen bad = total((missing(market_cap) | market_cap == 0) &
inrange(year, 2007, 2008)), by(firm)

drop if bad

For a more systematic review of similar technique, see
http://www.stata-journal.com/article.html?article=dm0055

Nick
[email protected]


On 22 March 2014 12:33, Julian Kochan <[email protected]> wrote:

> i have a set of data with financial firm characteristics of about 10.000 firms for Year 2000 - Year 2012.
>
> Let's assume: The first column of the data table displays the Name of the firm, the second the Year and the third displays the Market Capitalization.
> Thus, 13 rows in a row (2000-2012) display information about just one firm - just the year varies.
>
> Problem: I want to drop those firms, for which the Market Cap is zero or Missing in the Year 2007 or Year 2008.
>                  If this is the case, the firm should be dropped out of my data completely such that the firm observation is not only dropped for 2007 and 2008, but also for all the other year.
>                  I tried a lot but it didn't succeed. As you can see the condition is based on 3 Variables ( firm, market Cap and Year).
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