rats {mdhglm}

Rat Data

Description

The 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. Here each litter is treated as a cluster. The survival time is the time to development of tumor, measured in weeks. Death before occurrence of tumor yields a right-censored observation; forty rats developed a tumor, leading to censoring of about 73 percent.

Usage

data("rats")

Format

A data frame with 300 observations on the following 5 variables.

litter

cluster number for 50 litters

rx

tratment (1=drug, 0=placebo)

time

time to development of tumor, measured in weeks

status

status (1=occurrence of event, 0=censoring)

sex

a factor with levels f (female) and m (male)

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.