#Biostatistics 402

#GLM F-TEST OF FM VS RM

K=read.table("KNNLCh9SurgicalUnit.txt")
K
attach(K)
options(digits=6)

#FITTING THE FULL LINEAR MODEL
FM=lm(Y~X1+X2+X3+X4+X5+factor(X6))

#FITTING A REDUCED LINEAR MODEL
RM=lm(Y~X1+X2+X3+X5)

#COMPARING MODELS
anova(FM)
anova(RM)

#DEGREES OF FREEDOM
n=length(Y)
n
dfF = summary.lm(FM)$df[2]
dfF
dfR = summary.lm(RM)$df[2]
dfR

#SUMS OF SQUARES ERROR
SSEF = summary(FM)$sigma^2*summary(FM)$df[2]
SSEF
SSER = summary(RM)$sigma^2*summary(RM)$df[2]
SSER

#GLM TEST F-STATISTIC
F=((SSER-SSEF)/(dfR-dfF))/(SSEF/dfF)
F

#ANOVA GLM F-TEST
anova(RM,FM)