Random samples of ten mature (five-year-old and older) and ten two-year-old
cows were taken from each of five breeds. The average butterfat percentage
of these 100 cows is stored in the variable butterfat with the type
of cow stored in the variable breed and the age of the cow stored in
the variable age.
A data frame with 100 observations on the following 3 variables:
average butterfat percentage
a factor with levels 2 years old and
Mature
a factor with levels Ayrshire,
Canadian, Guernsey, Holstein-Friesian, and
Jersey
Canadian record book of purebreed diary cattle.
Sokal, R. R. and Rohlf, F. J. (1994) Biometry. W. H. Freeman, New York, third edition.
summary(aov(butterfat ~ breed + age, data = Cows))#> Df Sum Sq Mean Sq F value Pr(>F) #> breed 4 34.32 8.580 49.909 <2e-16 *** #> age 1 0.21 0.207 1.204 0.275 #> Residuals 94 16.16 0.172 #> --- #> Signif. codes: 0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1