Nick
[email protected]
> -----Original Message-----
> From: [email protected]
> [mailto:[email protected]]On Behalf Of Nick Cox
> Sent: 01 June 2006 16:04
> To: [email protected]
> Subject: RE: st: RE: Goodness of fit using Cox-snell residuals
>
>
> It just makes no sense to feed the Cox-Snell
> residuals to -stset-. You already set up
> the survival problem using -date_visit-.
>
> Once you have the Cox-Snell residuals, there
> are various things you can usefully do with them, but
> feeding them to -stset- is not one of those
> things.
>
> As -stset-is telling you, many of the residuals
> are negative, so the operation makes no sense on that ground
> alone..
>
> Nick
> [email protected]
>
> Emelda Okiro
>
> > Calrification
> > Am using stata 8
> > This is what my data looks like
> >
> > Id sex date_visit age failure
> > 1 0 04jun2004 28 0
> > 1 0 12jun2004 28 0
> > 1 0 18jun2004 28 0
> > 1 0 16jul2004 29 0
> > 1 0 13aug2004 30 0
> > 2 0 01mar2002 0 0
> > 2 0 27mar2002 1 0
> > 2 0 15apr2002 2 0
> > 2 0 18apr2002 2 1
> > 2 0 29apr2002 2 0
> >
> > basic time scale is calender time declared on the stset
> > origin and scale control the mapping from the basic time
> > scale onto the
> > time scale on which the analysis is to be performed
> > .
> > . stset date_visit, id (rsv) failure(lrti) enter(time
> > date_origin)origin(time d(31jan2002)) exit(time date_exit) scale(1)
> >
> > id: rsv
> > failure event: lrti != 0 & lrti < .
> > obs. time interval: (date_visit[_n-1], date_visit]
> > enter on or after: time date_origin
> > exit on or before: time date_exit
> > t for analysis: (time-origin)
> > origin: time d(31jan2002)
> >
> > --------------------------------------------------------------
> > ----------------
> > 29979 total obs.
> > 0 exclusions
> > --------------------------------------------------------------
> > ----------------
> > 29979 obs. remaining, representing
> > 469 subjects
> > 952 failures in multiple failure-per-subject data
> > 377180 total analysis time at risk, at risk from t = 0
> > earliest observed entry t = 0
> > last observed exit t = 1177
> >
> >
> >
> > . **** Checking the goodness of fit of the final model
> > . * evaluated by using Cox-Snell residuals
> > . * if the model fits the data well then the true cumulative hazard
> > function conditional on the covariate vector should have an
> > exponential
> > distribution with a hazard rate of one
> > . quietly xi: stcox i.currentagegrp sex i.siblings_un6 i.main_fuel
> > i.hse_toilet i.babies_bor i.education i.family_children
> > i.interaction_un6 i.siblingssch_un6 i.siblingsroom_ov6 i.female_sibs
> > poor i.weaning i.job_desc, nohr mgale(mg)
> >
> > . * compute cox-snell residuals
> > . predict cs, csnell
> > (663 missing values generated)
> >
> > . *re stset using cs residuals as the time variable (look at
> > the output)
> > the missing values are truly missing but it is omitting some of the
> > observations ????? It is also assuming single failure single record
> > which is incorrect as shown above my data set has multiple records
> > multiple failure-per-subject data.
> >
> > . stset cs, failure(lrti)
> >
> > failure event: lrti != 0 & lrti < .
> > obs. time interval: (0, cs]
> > exit on or before: failure
> >
> > --------------------------------------------------------------
> > ----------------
> > 29979 total obs.
> > 663 event time missing (cs>=.)
> > PROBABLE
> > ERROR
> > 1046 obs. end on or before enter()
> > --------------------------------------------------------------
> > ----------------
> > 28270 obs. remaining, representing
> > 925 failures in single record/single failure data
> > 925 total analysis time at risk, at risk from t = 0
> > earliest observed entry t = 0
> > last observed exit t = .8936376
> >
> > Does anyone know how cs residuals are computed in this kind
> > of data and
> > how I can specify multiple failure multiple recors when using cs
> > residuals as the time variable
>
> *
> * For searches and help try:
> * http://www.stata.com/support/faqs/res/findit.html
> * http://www.stata.com/support/statalist/faq
> * http://www.ats.ucla.edu/stat/stata/
>
*
* For searches and help try:
* http://www.stata.com/support/faqs/res/findit.html
* http://www.stata.com/support/statalist/faq
* http://www.ats.ucla.edu/stat/stata/
