This means that for each pair of
13 logs, that is 78 pairs total, we defined that a beetle species:
(i) prefers the first tree species if its rank is higher, (ii) prefers
the second tree species if its rank is higher or (iii) does not prefer
one tree species over the other if both tree species have the
same rank. The BT model allows us to estimate the probabilities
for each of the three possible outcomes.