#Presence and ansence of lucanid larvae

Nut<-as.data.frame(read.table(file="Nut_stag.txt",header=TRUE))
head(Nut)
class(Nut$decay_class)
class(Nut$diameter)
Nut$decay_class<- as.factor(Nut$decay_class)
levels(Nut$decay_class)
is.ordered(Nut$decay_class)
Nut$decay_class <-ordered(Nut$decay_class, levels=c("2","3","4","5","6"))
is.ordered(Nut$decay_class)
par(mfrow=c(1,2))
plot(Nut$larva,  Nut$decay_class, xlab= "Lucanid larvae presence", ylab= "Decay class")
plot(Nut$larva,  Nut$diameter, xlab= "Lucanid larvae presence", ylab= "Log diameter")
table (Nut$larva,  Nut$decay_class)
modelNut1<- glm(Nut$larva  ~Nut$decay_class*Nut$diameter, family=binomial)
summary(modelNut1)