--- On Thu, 3/9/09, Johannes Schoder wrote:
> I am estimating the lifetables for a
> certain group, e.g. people
> diagnosed with cancer type i living in county
> c in year t; This can be done by:
>
> ltable time_in_months, by (i c t)
> However Stata tells me:
> "by(): too many variables specified"
> It only works out when I include just one
> variable in the brackets of the by command.
The trick is to combine these different
variables into one variable. Here the -egen-
function -group()- is useful. See the example
below:
*----------- begin example ------------
sysuse cancer, clear
sum age
gen old = age > r(mean)
label define old 1 "old" 0 "young"
label value old old
egen groups = group(drug old) , label
ltable studytime, by(groups)
*----------- end example -------------
( For more on how to use examples I sent to statalist see:
http://www.maartenbuis.nl/stata/exampleFAQ.html )
Hope this helps,
Maarten
--------------------------
Maarten L. Buis
Institut fuer Soziologie
Universitaet Tuebingen
Wilhelmstrasse 36
72074 Tuebingen
Germany
http://www.maartenbuis.nl
--------------------------
*
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