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RE: st: dropping values
From
"Nick Cox" <[email protected]>
To
<[email protected]>
Subject
RE: st: dropping values
Date
Tue, 8 Jun 2010 15:29:11 +0100
This is the classic precision problem. -search precision- for FAQs,
articles, etc. and note that Stata struggles to cope with 0.2 as a exact
binary, as well it might.
. di %23.18f 0.2
0.200000000000000010
. di %21x 0.2
+1.999999999999aX-003
. di %21x 2
+1.0000000000000X+001
Nick
[email protected]
[email protected]
I think there is a problem with dropping values of a variable.
I have a variable named so2conc and it has values 0 .2 .25 .3 .4 .5 .6
1.0
If I use
drop if so2conc==0.2
nothing gets dropped.
If I use
egen so2=group(so2conc)
and then
drop if so2==2
then I get dropped what I need dropped.
I think the problem is that so2conc is stored as a real value.
Has anyone else had this problem or is there something written about
avoiding this problem?
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