rats {frailtyHL}

Rats data

Description

Rats data set presented by Mantel et al. (1977) is based on a tumorigenesis study of 50 litters of female rats. For each litter, one rat was selected to receive the drug and the other two rats were placebo-treated controls. The survival time is the time to the development of tumor, measured in weeks. Death before occurrent of tumor yields a right-censored observation; 40 rats developed a tumor, leading to censoring of about 73 percent.

Usage

data("rats")

Format

A data frame with 150 observations on the following 4 variables.

litter

Litter number for 50 female rats

rx

Treatment(1=drug, 0=placebo)

time

Time to the devlopment of tumor in weeks

status

Censoring indicator(1=uncensored, 0=censored)

References

Mantel,N., Bohidar N. R. and Ciminera, J. L. (1977). Mantel-Haenszel analyses of litter-matched time-to-response data, with modifications for recovery of interlitter information. Cancer Research, 37, 3863-3868.

Therneasu, T. (2012). survival: survival analysis, including penalised likelihood. http://CRAN.Rproject. org/package=survival. R pakcage version 2.36-14.