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st: Re: R: Survival Analysis Censoring stset


From   Dirk Volland <vollanddirk@googlemail.com>
To   statalist@hsphsun2.harvard.edu
Subject   st: Re: R: Survival Analysis Censoring stset
Date   Thu, 18 Sep 2008 18:57:46 +0300

Hello again,

thank you Carlo. It seems that my description has been a little
confusing. So here another try:

(1) The structure of the data with multiple episodes for each id is

 id | year0 | year1 | failure

1 | 2002 | 2003 | 0
1 | 2003 | 2004 | 0
1 | 2004 | 2005 | 1

stset with the command

stset year1, id(id) failure(failure)

With no gaps I meant that annual data is always available (2002 2003
2004 ... without missing years). Is this data interval censored just
because it is discrete and the failure event can only be measured at
year1 meaning the exact time between year0 and year1 is not available?
Is this handled by Stata in an appropriate manner?

(2) When I stset data with the command

stset year1, id(id) origin(time founding) enter(time start)

Here founding contains the time when the subject first came at risk
and start contains the time the observation window starts. So in a way
I know when a company was founded, but I want to start analysis in a
certain year. Are these observations still left censored (in
comparison to just deleting records that are prior to the observation
window)? Is this handled by Stata?

Thanks a lot,

dirk

2008/9/18 Carlo Lazzaro <carlo.lazzaro@tin.it>:
> Dear Dirk,
> as far as your first question is concerned:
>
> - it seems to me that your following statements "time span as 2006 and 2007
> without gaps" and "the exact time between year0 and year1" conflate.
> Should your analysis start in 2006 (that is, t0)and stop in 2007 (that is,
> t1), some companies will have gone to bankruptcy (that is failure=1) and
> other will have survived (that is, failure=0). The latter are right-censored
> observations, since they might go to bankruptcy (or not) in the future and,
> anyhow you will not know, since you have stopped your analysis.
> - stset - will automatically account for censored observations.
>
> For further details on this topic, I will recommend you to take a thorough
> look at:
>  Cleves MA, Gould WG, Gutierrez R. An Introduction To Survival Analysis
> Using Stata. 2nd edition. College Station: StataPress, 2006;
> [ST] Stata manual. Survival analysis and epidemiological table. Release 9
>
> Two other relevant contributors of the Statalist - Maarten Buis
> (http://home.fsw.vu.nl/m.buis/)  and Stephen Jenkins
> (http://www.iser.essex.ac.uk/teaching/degree/stephenj/ec968/index.php.)
> published really interesting papers as well as teaching-notes on the topics
> you are interested in.
>
> HTH and Kind Regards,
>
> Carlo
>
> -----Messaggio originale-----
> Da: owner-statalist@hsphsun2.harvard.edu
> [mailto:owner-statalist@hsphsun2.harvard.edu] Per conto di Dirk Volland
> Inviato: giovedý 18 settembre 2008 15.29
> A: statalist@hsphsun2.harvard.edu
> Oggetto: st: Survival Analysis Censoring stset
>
> Hello,
>
> i have to quesitons regarding censoring and how it is handled in
> Stata's survival package.
>
> (1) When I have the following data structure:
>
>  id | year0 | year1 | failure
>
> stset with the command
>
> stset year1, id(id) failure(failure)
>
> and year0 and year1 always represents a time span as 2006 and 2007
> without gaps. Is this data interval censored just because it is
> discrete and the failure event can only be measured at year1 meaning
> the exact time between year0 and year1 is not available? Is this
> handled by Stata in an appropriate manner?
>
> (2) When I stset data with the command
>
> stset year1, id(id) origin(time founding) enter(time start)
>
> Here founding contains the time when the subject first came at risk
> and start contains the time the observation window starts. So in a way
> I know when a company was founded, but I want to start analysis in a
> certain year. Are these observations still left censored? Is this
> handled by Stata?
>
> Thanks for any help,
>
> best wished,
>
> dirk
>
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>
>



-- 
Dirk Volland
mobile   +358468948277
skype      junin7
! new Email: vollanddirk@gmail.com



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