Breathing Test
Effects of age and smoking status on breathing test results for workers in industrial plants in Texas.
data(breath)
A data frame with 18 observations on the following 4 variables.
a factor with levels <40 40-59
number of workers in group
a factor with levels Current.smoker
Former.smoker Never.smoked
a factor with levels Abnormal
Borderline Normal
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.
Ludwig Fahrmeir, Gerhard Tutz (1994): Multivariate Statistical Modelling Based on Generalized Linear Models. Springer Series in Statistics. Springer Verlag. New-York Berlin Heidelberg
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
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