Bookmark and Share

Notice: On March 31, it was announced that Statalist is moving from an email list to a forum. The old list will shut down at the end of May, and its replacement, statalist.org is already up and running.


[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: st: RE: RE: estimation with a time trend.


From   Maarten buis <maartenbuis@yahoo.co.uk>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: RE: RE: estimation with a time trend.
Date   Mon, 5 Jul 2010 05:14:56 -0700 (PDT)

--- On Mon, 5/7/10, natasha agarwal wrote:
> I am afraid I did not understand "year- (or -year-
> MINUS> midpoint) for interpretability?"

Say you have a variable representing year of birth
ranging between 1910 and 1980. I would then usually
have a line like this in my do-file:

gen c_year = year - 1910

Afterwards I would use c_year instead of year. In
this case "midpoint" is 1910, and makes sure that
your new variable is shifted to the left such that
it has the value zero in 1910. This makes sure 
that the baseline in your models refer to a point 
at the beginning of your observed period. This is 
particularly important if you include interactions 
or if you care about the constant (e.g. in a random 
effects model)

Hope this helps,
Maarten

--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany

http://www.maartenbuis.nl
--------------------------


      

*
*   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/


© Copyright 1996–2014 StataCorp LP   |   Terms of use   |   Privacy   |   Contact us   |   Site index