674
Le logiciel R
13.2- rendement <- c(8,11,11,10,7,12,13,14,11,10,10,12,12,13,14,17,
13,17,14,13,8,9,8,10,9,10,7,10,12,11,11,9,11,
11,12,13,12,11,15,14)
aliment <- as.factor(rep(rep(1:4,each=5,2)))
levels(aliment) <- c("Paille","Foin","Herbe","Aliments ensil´ es")
dose <- as.factor(rep(1:2,each=20))
levels(dose) <- c("faible", "forte")
laitier <- data.frame(rendement=rendement, aliment= aliment,
dose=dose)
interaction.plot(aliment,dose,rendement)
interaction.plot(dose,aliment,rendement)
13.3- summary(lm(rendement∼dose * aliment))
13.4- anova(lm(rendement∼dose * aliment))
Interaction non significative : on pr´ ef` erera un mod` ele plus simple.
13.5- anova(lm(rendement∼dose+aliment))
• ´
Etude sur l’intima-m´ edia
13.1- url <- "http://biostatisticien.eu/springeR/Intima_Media.txt"
intima.media <- read.table(url,header=TRUE,dec=",",sep=" ")
attach(intima.media)
13.2- Mod` ele ANOVA ` a deux facteurs avec un terme d’interaction.
13.3- tabac <- factor(tabac)
alcool <- factor(alcool)
interaction.plot(tabac,alcool,mesure)
interaction.plot(alcool,tabac,mesure)
13.4- require("car")
modele.intima <- Anova(lm(mesure∼alcool * tabac),type="III")
modele.intima
# interaction non-significative:
modele.intima.additif <- Anova(lm(mesure∼alcool+tabac),type="III")
# alcool: pvaleur=0.09 Tabac: p-valeur=0,16