| pseudomean {pseudo} | R Documentation |
Computes pseudo-observations for modeling survival function based on the restricted mean.
pseudomean(time,event, tmax)
time |
the follow up time. |
event |
the status indicator: 0=alive, 1=dead. |
tmax |
the maximum cut-off point for the restricted mean. If missing or larger than the maximum follow up time, it is replaced by the maximum follow up time. |
The function calculates the pseudo-observations for the restricted mean survival for each individual at prespecified time-points. The pseudo-observations can be used for fitting a regression model with a generalized estimating equation.
A data frame. The first two columns contain the follow up time and the status indicator as given by the user. The third column presents the computed pseudo-observations.
Klein J.P., Gerster M., Andersen P.K., Tarima S.: "SAS and R Functions to Compute Pseudo-values for Censored Data Regression." Department of Biostatistics, University of Copenhagen, research report 07/11.
library(KMsurv)
data(bmt)
#compute the pseudo-observations:
pseudo = pseudomean(time=bmt$t2, event=bmt$d3,tmax=2000)
#arrange the data
a <- cbind(bmt,pseudo = pseudo$psumean,id=1:nrow(bmt))
#fit a regression model for the mean time
library(geepack)
summary(fit <- geese(pseudo ~ z1 + as.factor(z8) + as.factor(group),
data = a, id=id, jack = TRUE, family=gaussian,
corstr="independence", scale.fix=FALSE))
#rearrange the output
round(cbind(mean = fit$beta,SD = sqrt(diag(fit$vbeta.ajs)),
Z = fit$beta/sqrt(diag(fit$vbeta.ajs)), PVal =
2-2*pnorm(abs(fit$beta/sqrt(diag(fit$vbeta.ajs))))),4)