#Biostatistics 450

#RXC CONTINGENCY TEST
#ZAR EXAMPLE 23.1

#DATA KEYED INTO MATRIX:
X=matrix(c(32,43,16,9,55,65,64,16),nrow=2,byrow=T)
X

chisq.test(X)

#HAND CALCULATION OF G TEST:
O=matrix(chisq.test(X)$observed)
O
E=matrix(chisq.test(X)$expected)
E

#G STATISTIC:
G=2*sum(O*log(O/E))
G

#CRITICAL VALUE:
alpha=0.05
k=4
g=0
df=k-g-1
C=qchisq(1-alpha,df)
C

#PROBABILITY:
P=(1-pchisq(G,df))
P

#DATA FROM A (DIFFERENT) ORIGINAL DATASET IN R FORMAT:
ROS=read.table("RosnerTA3.11.txt")
ROS
attach(ROS)

#CREATING CONTINGENCY TABLE:
T=table(Antibo,Age)
T

chisq.test(T)