mammary: Ability of retinyl acetate to prevent mammary cancer in rats

In glmtoolbox: Set of Tools to Data Analysis using Generalized Linear Models

Ability of retinyl acetate to prevent mammary cancer in rats

Description

A total of 76 female rats were injected with a carcinogen for mammary cancer. Then, all animals were given retinyl acetate (retinoid) to prevent mammary cancer for 60 days. After this phase, the 48 animals that remained tumor-free were randomly assigned to continue retinoid prophylaxis or control. Rats were then palpated for tumors twice weekly, and observations ended 182 days after initial carcinogen injections began. The main objective of the analysis was to assess the difference in tumor development between the treated and control groups.

Usage

data(mammary)

Format

A data frame with 48 rows and 2 variables:

group

a factor giving the group to which the rat was assigned: "retinoid" or "control".

tumors

a numeric vector giving the number of tumors identified on the rat.

References

Lawless J.F. (1987) Regression Methods for Poisson Process Data. Journal of the American Statistical Association 82:808-815.

Morel J.G., Nagaraj N.K. (2012) Overdispersion Models in SAS. SAS Institute Inc., Cary, North Carolina, USA.

Examples

data(mammary)
dev.new()
boxplot(tumors ~ group, data=mammary, outline=FALSE, xlab="Group",
        ylab="Number of tumors", col=c("yellow","blue"))

glmtoolbox documentation built on Oct. 10, 2023, 9:06 a.m.