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Re: st: restrict subjects for analysis from multi-record data


From   "KUBO Tatsuhiko" <kubo@med.uoeh-u.ac.jp>
To   <statalist@hsphsun2.harvard.edu>
Subject   Re: st: restrict subjects for analysis from multi-record data
Date   Tue, 7 Oct 2008 18:48:28 +0900

Dear Michael,

Thank you very much for a such quick reply! Would you mind if I ask you some 
more details.

Because my database is multi-record one (datas are annualy recorded for each 
ID), I want to distinguish covariate between baseline and endpoint.

How can I restrict the subjects to "smokers at baseline", and to "smoker at 
endpoint"?

e.g. make analysis only among subjects who are smokers (smoke==1) at the 
time of the baseline(_t0==0).
         * stcox Exposure Covariate1 Covariate2 if smoke==1 ??
e.g. make analysis only among subjects who are smokers at the time of the 
endpoint.
         * stcox Exposure Covariate1 Covariate2 if smoke==1 ??


I am using "stcox" and "sts graph(Kaplan-Meier)" commands.
Thank you in advance.

Tastauhiko KUBO


----- Original Message ----- 
From: "Michael McCulloch" <mm@pinest.org>
To: <statalist@hsphsun2.harvard.edu>
Sent: Tuesday, October 07, 2008 10:36 AM
Subject: Re: st: restrict subjects for analysis from multi-record data


Hello Tatasuhiko,
If you are using the command -stcox-, then you restrict using the
-if- command, for example:

stcox MainExposure Covariate1 Covariate2 if smoke==1

Distinguishing between baseline and endpoint would need other
variables, which can also be used after -if-.
Michael

>Dear colleges,
>
>I am now making a survival analysis using the multi-record data.
>
>Now, I want to restrict the subjects for analysis regarding their life
>styles.
>   >>  e.g. make analysis only among subjects who are smokers (smoke==1) at
>the time of the baseline(_t0==0).
>   >>  e.g. make analysis only among subjects who are smokers at the time 
> of
>the endpoint.
>
>In this case what command should be used to restrict the subjects?
>
>
>Thank you.
>
>
>From Tatasuhiko KUBO 

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