A Guide to Doing Statistics in Second Language Research Using R

Chapter 9: T-Tests


# 9.1 箱ひげ図の作成
boxplot(recprescore~group, ylab="recprescore", xlab="group", data=leow)
identify(leow$group, leow$recprescore)



# 9.1.2 従属変数の連鎖の箱ひげ図（対応あるt検定）
attach(french)
boxplot(anwr_1,anwr_2,enwr_1,enwr_2,ylab="Score on test out of 40",
names=c("Arabic Time 1","Arabic Time 2","English Time 1","English Time 2"),las=1,notch=TRUE,col="grey",boxwex=.5,ylim=range(c(1,40)),medcol="white")



# 9.1.3 グループに分かれた従属変数の箱ひげ図
par(mfrow=c(1,2))
levels(leow$group)=c("NTA", "ThinkAloud") #Make labels shorter so they‘ll print
boxplot(proprescore~group,data=leow,ylim=range(c(0,5)),col="gray", main="Productive pre-tests",boxwex=.5)
boxplot(propostscore~group,data=leow,ylim=range(c(0,5)),col="gray", main="Productive post-tests",boxwex=.5)



# 9.3独立サンプルt検定の実行
t.test(propostscore~group, alternative='two.sided', conf.level=.95, 
var.equal=FALSE, data=leow)



＃9.4 Robust独立サンプルt検定の実行
* WRSが用いられない*
>Library(WRS)
>propostscoreNTA <- subset(leow, subset=group=="NTA", select=c(propostscore)) #n=30
propostscoreTA <- subset(leow, subset=group=="ThinkAloud", select=c(propostscore)) #n=37
trimpb2 (propostscoreNTA, propostscoreTA, tr=.2, alpha=.05, nboot=2000, win=F) 



# 9.6 対応のあるt検定の実行
#アラビア語
t.test(french$anwr_1,french$anwr_2,alternative='two.sided', 
conf.level=.95, paired=TRUE)

＃英語
t.test(french$enwr_1,french$enwr_2,alternative='two.sided', 
conf.level=.95, paired=TRUE)




# 9.7 Robust対応のあるt検定 
* WRSが用いられない*
rmmcppb(french$ANWR_1, french$ANWR_2, alpha=.05, est=mean, tr=.2, dif=T, nboot=2000, BA=T, hoch=F) 



# 9.9 1標本t検定を実行する
t.test(torres$grammar, alternative='two.sided', mu=3, conf.level=.95) 



#9.10  Robust1標本t検定の実行
* WRSが用いられない*
trimpb(torres$grammar, tr=.2, alpha=.05, nboot=2000,WIN=F,null.value=3)
mean(torres$PRON,tr=.2)


https://onlinecourses.science.psu.edu/statprogram/node/138

propostscoreNTA <- subset(leow, subset=group=="NTA", select=c(propostscore)) #n=30
propostscoreTA <- subset(leow, subset=group=="ThinkAloud", select=c(propostscore)) #n=37

trimpb2 (propostscoreNTA, propostscoreTA, tr=.2, alpha=.05, nboot=2000, win=F, plotit=T)


http://127.0.0.1:22644/library/WRS2/html/00Index.html