#Biostatistics 400

#MULTIPLE REGRESSION MODEL SS
#ZAR EXAMPLE 20.1a
ZAR=read.table("ZarEX20.1aR.txt")
ZAR
attach(ZAR)

Y=var5
X1=var1
X2=var2
X3=var3
X4=var4

#DOWNLOAD {CAR} PACKAGE FROM CRAN:
library(car)
#TYPE 2 SS:

FM=lm(Y~X1+X2+X3+X4)
summary(FM)
Anova(FM)
drop1(FM)  # equivalent to Anova() but also gives AIC

#REDUCED MODELS:
RM1=lm(Y~X2+X3+X4)  #subtracting X1
RM2=lm(Y~X1+X3+X4)  #subtracting X2
RM3=lm(Y~X1+X2+X4)  #subtracting X3
RM4=lm(Y~X1+X2+X3)  #subtracting X4

Anova(RM1)
Anova(RM2)
Anova(RM3)
Anova(RM4)

TYPE 1 SS:
anova(FM)

FM1=lm(Y~X1+X2)
RM1=lm(Y~X1)
anova(FM1)
anova(RM1)