# falls noch nicht installiert:
install.packages("EffectStars2")

library(EffectStars2) # für Daten
library(VGAM)         # Schätzung I
library(nnet)         # Schätzung II

data(election)  # Data from 2009

levels(election$Partychoice)

table(election$Partychoice)
round(100*table(election$Partychoice) / nrow(election),2)
barplot(100*table(election$Partychoice)/nrow(election), 
        col = c("black", "red", "yellow", "green", "pink"), 
        las = 1, ylab = "Percentage [%]")

# Geschlecht mit Referenz CDU
m1 <- vglm(Partychoice ~ Gender, data = election, 
                family = multinomial(refLevel = "CDU"))
# Geschlecht mit Referenz SPD
m2 <- vglm(Partychoice ~ Gender, data = election, 
                family = multinomial(refLevel = "SPD"))

# anderes Paket
m3 <- multinom(Partychoice ~ Gender, data = election)

# get probabilities
predict(m1, newdata = data.frame(Gender = "female"), 
        type = "response")
predict(m1, newdata = data.frame(Gender = "male"), 
        type = "response")


predict(m3, newdata = data.frame(Gender = "female"), 
        type ="probs")


m_elect <- vglm(Partychoice ~ Gender + West + Age + 
                  Union + Highschool, family = multinomial(refLevel = "CDU"), data = election)

n_elect <- multinom(Partychoice ~ Gender + West + Age + Union + Highschool,  data = election)


summary(m_elect)
summary(n_elect)

effectstars(m_elect, symmetric = FALSE)

effectstars(m_elect)


m_elect2 <- vglm(Partychoice ~ Gender + West + Age + Union + Highschool + Unemployment
                 + Pol.Interest + Democracy + Religion, 
                 family = multinomial(refLevel = "Greens"), 
                 data = election)

summary(m_elect2)

effectstars(m_elect2)
effectstars(m_elect2, symmetric = FALSE)