Notice: On April 23, 2014, Statalist moved from an email list to a forum, based at statalist.org.
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
st: AW: lag
From
"Klaus Pforr" <[email protected]>
To
<[email protected]>
Subject
st: AW: lag
Date
Thu, 31 May 2012 11:06:00 +0200
<>
Dear Fabian,
I think that are correctly expecting that "sale[_n-4]" is missing for the first for observations. The problem is, that "sale[_n-4]" is evaluated as "." for _n<=4, but the boolean expression "sale<=sale[_n-4]" is - at least not necessarily - evaluated as missing for these obs. As sale is probably less than the pseudo-infinitely large "." (See: help missing), you will have "sale_decrease5=1" for these observations.
To catch this problem, you can add the assertion "& sale[_n-4]!=." to you if-condition.
best
Klaus
__________________________________
Klaus Pforr
GESIS -- Leibniz Institut für Sozialwissenschaft
B2,1
Postfach 122155
D - 68072 Mannheim
Tel: +49 621 1246 298
Fax: +49 621 1246 100
E-Mail: [email protected]
__________________________________
-----Ursprüngliche Nachricht-----
Von: [email protected] [mailto:[email protected]] Im Auftrag von "Fabian Schönenberger"
Gesendet: Donnerstag, 31. Mai 2012 10:52
An: [email protected]
Betreff: st: lag
Dear Statalist
With the following command I want to generate a dummy variable; 1 if current sales are lower than 4 years ago, 0 if sales are larger for each company:
by cusip: generate sale_decrease5=0 if sale>sale[_n-4] by cusip: replace sale_decrease5=1 if sale<=sale[_n-4]
I expected for each cusip 4 missings at the beginning, since there is no _n-4. However, the command gives 1 for each cusip in the first four years.
How do I have to adapt the formula to get dummy variables after the first 4 years passed?
Many thanks in advance.
Fabian
--
NEU: FreePhone 3-fach-Flat mit kostenlosem Smartphone!
Jetzt informieren: http://mobile.1und1.de/?ac=OM.PW.PW003K20328T7073a
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
*
* For searches and help try:
* http://www.stata.com/help.cgi?search
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/