#Biostatistics 260

#ONE-WAY ANOVA CONTRASTS

ZAR=read.table("ZarEX11.1R.txt")
ZAR
attach(ZAR)
Y=conc
X=factor(code)
options(digits=12)

#DESCRIPTIVE STATISTICS:
N=length(Y)
N
k=5
#MEANS:
Xbar=tapply(Y,ZAR[,-1],mean)
Xbar
#NUMBERS:
tapply(Y,ZAR[-1],length)
#STANDARD DEVIATIONS:
tapply(Y,ZAR[-1],sd)

#GENERATING ANOVA TABLE:
FM=lm(Y~X)
anova(FM)

#MAKING CONTRASTS IN R
require(gmodels) #MUST LOAD {gmodels} PACKAGE FROM CRAN
#CONTRAST FOR ZAR Example 11.5
C1=c(0,1/3,1/3,1/3,-1)
fit.contrast(FM,X,C1,conf.int=0.95)
C2=c(1,-1/3,-1/3,-1/3,0)
fit.contrast(FM,X,C2,conf.int=0.95)
C3=c(1/2,-1/3,-1/3,-1/3,1/2)
fit.contrast(FM,X,C3,conf.int=0.95)
C4=c(1/2,-1/2,-1/2,1/2,0)
fit.contrast(FM,X,C4,conf.int=0.95)