Data=read. table ("ZarEX7.4.txt",header=T)
Data

X=factor(Gender)
Y=Salary
LM=lm(Y~X)
LM
summary(LM)
anova(LM)
Y=Salary
 X1=Gender
 X2=factor(Rank)
 X3=factor(Dept)
X4=factor(Years)
 X5=Merit
 LM=lm(Y~X1+X2+X3+X4+X5)
 LM
summary(LM)
anova(LM)

Install car package
anova(LM)
extractAIC(LM)

RM1=lm(Y~X1+X2+X3+X4)
extractAIC(RM1)

RM2=lm(Y~X1+X2+X3)
extractAIC(RM2)

drop1(LM)
step(LM)

FullModel=LM
 ReducedModel=lm(Y~X1+X2+X3+X5)
anova(ReducedModel,FullModel)