data <- scan(what =list(treat="", y=0), multi.line=F)
  Standard 55   Standard 47   Standard 48
  One 55  One 64  One 64 
  Two 55  Two 49  Two 52 
  Three 50  Three 44  Three 41 

data

methods <- data.frame(data)
rm(data)

methods$treat <- as.factor(methods$treat)
methods$treat <- relevel(methods$treat, ref="Standard")     # setting the reference level for Dunnett

methods.lm <- lm(y ~ treat, data = methods)

anova(methods.lm) 
summary(methods.lm)


 # Dunnett's multiple comparison method

library(multcomp)

methods.Dunnett <- glht(methods.lm,linfct=mcp(treat="Dunnett"))

summary(methods.Dunnett)
plot(methods.Dunnett,sub="Dunnetts method")


 # Tukey's multiple comparison method

methods.Tukey  <- glht(methods.lm,linfct=mcp(treat="Tukey"))

summary(methods.Tukey)
plot(methods.Tukey,sub="Tukeys method")


 # check model assumptions

par(mfrow=c(2,2))  
plot(methods.lm)
par(mfrow=c(1,1))