ancova<-read.csv("경로/ancova.csv")
head(ancova)

#기술통계량
mean<-tapply(ancova$post, ancova$group, mean)
sd<-tapply(ancova$post, ancova$group, sd)
length<-tapply(ancova$post, ancova$group, length)stat<-rbind(mean,sd,length)
round(stat,2)

#ANCOVA
install.packages("HH")
library(HH)

ancova$group<-factor(ancova$group,levels=1:3, labels = c("기존치료","새로운 치료","방치"))

ancova1<-ancova(post ~ pre + group, data=ancova)
summary(ancova1)

#사후검정
install.packages("multcomp")
library(multcomp)

model = lm(post~group+pre,data=ancova)
tukey = glht(model,linfct=mcp(group="Tukey"))

summary(tukey)