require(foreign)
setwd(dirname(rstudioapi::getActiveDocumentContext()$path))


mathb=read.spss("mathb.sav")
a=data.frame(mathb)
mathbitems=a[,2:15]

#analise de items dicot?micos
##############################

require(psych)
alpha(mathbitems)
help(alpha)

require(epicalc)
alpha(vars=c(i01:i14), mathbitems)


require(psychometric)
item.exam(mathbitems, y=mathb$puntaje, discrim=TRUE)
help(item.exam)

#intervalo de Confian?a Bootstrap para alpha
require(ltm)
cronbach.alpha(mathbitems, CI=TRUE, B=500)

#Correla?ao ponto biserial

biserial.cor(rowSums(mathbitems), mathbitems[[1]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[2]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[3]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[4]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[5]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[6]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[7]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[8]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[9]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[10]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[11]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[12]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[13]], level = 2)
biserial.cor(rowSums(mathbitems), mathbitems[[14]], level = 2)

require(coefficientalpha)
alpha.mathb=cronbach(mathbitems)
plot(alpha.mathb,type="d")
summary(alpha.mathb)




#analise de items politomicos
###############################


atitudes=read.spss("baseunionfinal.sav")
a=data.frame(atitudes)
atitudesitems=a[,4:25]
psych::alpha(atitudesitems)

#analises de items por paises
atitudesP=subset(a,pais.=="Per?")
atitudesP
atitudesitemsP=atitudesP[,4:25]
alpha(atitudesitemsP)

atitudesE=subset(a,pais.=="Espa?a")
atitudesE
atitudesitemsE=atitudesE[,4:25]
alpha(atitudesitemsE)