#First Test
FIQ=read.table("C:/Users/Etta/Documents/FIQ.txt",header=TRUE)
FIQ
attach(FIQ)
Y=FSIQ
x1f=Weight
x2f=Height
x3f=MRI_Count
LMF=lm(Y~x1f+x2f+x3f)
LMF
summary(LMF)
anova(LMF)
step(LMF,direction="backward")
extractAIC(LMF)

#The tests below are based on calculations above and can be verified above.

FMF=lm(Y~x1f+x2f+x3f)
RMF=lm(Y~x2f+x3f)
anova(RMF,FMF)

#Second Test
VIQD=read.table("C:/Users/Etta/Documents/VIQ.txt",header=TRUE)
VIQD
attach(VIQD)
Y=VIQ
x1v=Weight
x2v=Height
x3v=MRI_Count
LMV=lm(Y~x1v+x2v+x3v)
LMV
summary(LMV)
anova(LMV)
step(LMV,direction="backward")
extractAIC(LMV)

#The tests below are based on calculations above and can be verified above.

FMV=lm(Y~x1v+x2v+x3v)
RMV=lm(Y~x2v+x3v)
anova(RMV,FMV)

#Third Test
PIQD=read.table("C:/Users/Etta/Documents/PIQ.txt",header=TRUE)
PIQD
attach(PIQD)
Y=PIQ
x1p=Weight
x2p=Height
x3p=MRI_Count
LMP=lm(Y~x1p+x2p+x3p)
LMP
summary(LMP)
anova(LMP)
step(LMP,direction="backward")
extractAIC(LMP)

#The tests below are based on calculations above and can be verified above.

FMP=lm(Y~x1p+x2p+x3p)
RMP=lm(Y~x2p+x3p)
anova(RMP,FMP)