search for: inftime

Hello Everyone,   I'm learning how to perform various statistical analyses in R. I'm checking my understanding by replicating examples from my SAS books. Below is an attempt to replicate a Cox Proportional Hazards model with a time-varying covariate. I think I'm doing this correctly but am not completely sure. I would appreciate it if someone could double-check my results. In case

Hi all I have a function of log defined by y = log(1- exp(-a)), when exp(-a) is greater, 1, it produce NaN. How can I remove this in R? [[alternative HTML version deleted]]

Hi R community, I have some data set and construct the likelihood as follows likelihood <- function(alpha,beta){ lh<-1 d<-0 p<-0 k<-NULL data<-read.table("epidemic.txt",header = TRUE) attach(data, warn.conflicts = F) k <-which(inftime==1) d <- (sqrt((x-x[k])^2+(y-y[k])^2))^(-beta) p<-1 - exp(-alpha*d) for(i in 1:100){ if(i!=k){ if(inftime[i]==0){ lh<-lh*(1-p[i]) } if(inftime[i]==2){ lh<-lh*p[i] } } } re...

Hello Everyone, I'm learning to do survival analysis in R using a time-varying covariate. I've managed to set up my data correctly using SAS and then to get the correct result using R. What I'd like help with is getting the data set up correctly in R without having to resort to using SAS. Below are two datasets. The first is the raw data I'm starting out with. The second is set