Re: st: Re: R: Survival Analysis Censoring stset

[Steven Samuels <sjhsamuels@earthlink.net>]

Dirk--

For how many years do you have outcomes?  "Interval-censored" data  
methods are, in my opinion, best applied to data in which there are  
many possible time points. I think your data are more properly  
classified as "grouped" or "discrete". With a relative small number  
of years of observation, I suggest calendar time as a time-scale.

This topic has come up before ( http://www.stata.com/statalist/ 
archive/2006-11/msg00473.html ).
I haven't reread the thread, but I suggest that you try a survival  
model appropriate for discrete data, either -hshaz- or -pgmhaz8- by  
Stephen Jenkins (-findit hshaz-/ -findit pgmhaz8-).  Control for  
company age with covariates.

Note that "left-censored" means the outcome for a company took place  
before the start of observation. You have "left-truncated" or  
"delayed entry" data: some of your companies are "survivors" of  
original cohorts of companies which started before the study.

-Steve
On Sep 18, 2008, at 11:57 AM, Dirk Volland wrote:


> 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: gioved� 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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