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#This is a file with executable R code for chapter 13 of Natalia Levshina's (2015) 
#How to Do Linguistics with R. Amsterdam/Philadelphia: John Benjamins. 
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###Section 13.2


##Main text

install.packages(c("mlogit", "polytomous"))

library(Rling); library(mlogit); library(polytomous)

data(let)

str(let)

let1 <- mlogit.data(let, shape = "wide", choice = "Verb")

nrow(let1)

m.let <- mlogit(Verb ~ 1 | Year + Reg + Permitter + Imper, data = let1, reflevel = 2)

summary(m.let)

exp(-0.1206881)

confint(m.let)

head(fitted(m.let))

head(let$Verb)

head(fitted(m.let, outcome = FALSE))

m.let1 <- mlogit(Verb ~ 1 | Year + Permitter + Imper, data = let1, reflevel = 2)

waldtest(m.let1, m.let)

m.let2 <- polytomous(Verb ~ Permitter + Imper + Year + Reg, data = let)

summary(m.let2)$statistics

print(summary(m.let2), parameter = "logodds")

round(m.let2$p.values, 3)

exp(-0.1203)

m.let3 <- polytomous(Verb ~ Permitter + Imper*Reg + Year, data = let)

anova(m.let2, m.let3)

print(summary(m.let3), parameter = "logodds")