Re: [R] time dependency of Cox regression

2004-11-03 Thread Thomas Lumley
On Wed, 3 Nov 2004, array chip wrote: Thanks very much for the suggestion. still some quiestions. In your example of splitting the covariate into 6 time-dependent covariates (6 records per person), will the survival time and censored status be the same for each of the 6 records? If that's the case,

Re: [R] time dependency of Cox regression

2004-11-03 Thread array chip
Thanks very much for the suggestion. still some quiestions. In your example of splitting the covariate into 6 time-dependent covariates (6 records per person), will the survival time and censored status be the same for each of the 6 records? If that's the case, how does the model know that each of

Re: [R] time dependency of Cox regression

2004-11-03 Thread Thomas Lumley
array chip wrote: Hi, How can I specify a Cox proportional hazards model with a covariate which i believe its strength on survival changes/diminishes with time? The value of the covariate was only recorded once at the beginning of the study for each individual (e.g. at the diagnosis of the disease)

R: [R] time dependency of Cox regression

2004-11-03 Thread Vito Muggeo
rame(cbind(a,bb),row.names=NULL) #if(!missing(epss)) A[,"stop"]<-A[,"stop"]+ifelse(A[,"stop"]==A[,"start"],epss,0) if(epss>0) A[,"stop"]<-A[,"stop"]+ifelse(A[,"stop"]==A[,"start"],epss,0)

Re: [R] time dependency of Cox regression

2004-11-02 Thread Frank E Harrell Jr
array chip wrote: Hi, How can I specify a Cox proportional hazards model with a covariate which i believe its strength on survival changes/diminishes with time? The value of the covariate was only recorded once at the beginning of the study for each individual (e.g. at the diagnosis of the disease)

[R] time dependency of Cox regression

2004-11-02 Thread array chip
Hi, How can I specify a Cox proportional hazards model with a covariate which i believe its strength on survival changes/diminishes with time? The value of the covariate was only recorded once at the beginning of the study for each individual (e.g. at the diagnosis of the disease), so I do not hav