breath {Fahrmeir}

Breathing Test

Description

Effects of age and smoking status on breathing test results for workers in industrial plants in Texas.

Usage

data(breath)

Format

A data frame with 18 observations on the following 4 variables.

Age

a factor with levels <40 40-59

n

number of workers in group

Smoking.status

a factor with levels Current.smoker Former.smoker Never.smoked

Breathing.test

a factor with levels Abnormal Borderline Normal

Details

We consider the effects of age and smoking status upon breathing test results for workers in industrial plants in Texas. The test results are given on an ordered scale with categories "Abnormal", "Borderline" and "Normal". It is of interest how age and smoking status are connected to breathing test results.

Source

Ludwig Fahrmeir, Gerhard Tutz (1994): Multivariate Statistical Modelling Based on Generalized Linear Models. Springer Series in Statistics. Springer Verlag. New-York Berlin Heidelberg

Examples

str(breath)
breath$Breathing.test <- ordered(breath$Breathing.test)
library(MASS)
breath.polr1 <- polr(Breathing.test ~ Age*Smoking.status, weight=n, 
                     data=breath)
breath.polr2 <- polr(Breathing.test ~ Age*Smoking.status, weight=n, 
                     data=breath, method="cloglog")
summary(breath.polr1)
summary(breath.polr2)
# continuation ratio models (as of page 89) might be fitted with
# Design or VGAM package.