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Re: st: Re: destringing


From   "Michael S. Hanson" <mshanson@mac.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Re: destringing
Date   Sat, 28 Aug 2004 12:08:20 -0400

On Aug 28, 2004, at 11:30 AM, Suzy wrote:

. tab dxcode1 if dxcode1==V3000
V3000 not found
r(111);
In your -if- statement, you told Stata to compare the variable dxcode1 with the variable V3000. And Stata responded: "V3000 not found" because you don't have a variable called V3000.



And this....

tab dxcode1 if dxcode1==27500  (just numeric)
type mismatch
r(109);
Stata knows from your -infix- command that the data type of variable dxcode1 is a string (specifically, str5 -- a 5-character string). You then asked Stata to compare a string variable with a numerical value -- but since these are different data types, Stata responded "type mismatch".



That's why I then went ahead and used the destring (and force) option...which made the dash and alpha-numerics disappear as missing datapoints - but did allow me to read the pure numeric numbers under these variable names.
Which seems unnecessary. Have you tried:

tab dxcode1 if dxcode1 == "V3000"
tab dxcode1 if dxcode1 == "27500"

(By the way, are you sure you aren't interested in tabulating the values of *another* variable when dxcode1 takes on particular values?)



Stata technicians did not tell me that when I added the str5 and str4 to those variables during infix - that my data would not be able to be read. So this is the full story.
They did not tell you that because that would not be a correct statement. You can read the data -- and you can use conditional statements by telling Stata to compare string variables with strings (i.e. values in "quotes").

Hope this helps.

-- Mike

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