[R] Censboot Warning and Error Messages

[Prof Brian Ripley]

On Mon, 7 Jun 2004, Jingky Lozano wrote:

> Good day R help list!!!
> 
> I've been trying to do Bootstrap in R on Censored data.  I encountered
> WARNING/ERROR messages which I could not find explanation.
> I've been searching on the literature for two days now and still can't find
> answers.  I hope there's anyone out there who can help me 
> with these two questions: 
> 
> 1. If the "Loglik converged before variable..." message appears (please see
> printout below) while doing ordinary bootstrap,
> does it mean that I cannot trust the result of the bootstrap statistics?  Is
> there a valid way to resolve it like increase the sample size?

This is a message from coxph and nothing at all to do with censboot.

> 2. In doing conditional bootstrap with survival data, how can one handle a data
> with two largest survival time observations (ties)
> but one is censored while the other is not.  For example, if the censoring time
> is 48 months and a patient died exactly at that time, he will
> have the same survival time as another patient who was also observed to lived 48
> months long but classified as censored because he was still 
> alive at the set censoring time.  Doing the recommended algorithm in R gives an
> "error in sample length..." message.

Recommended by whom?  You could break the ties (death first) and avoid the 
problem.

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595