The large number of mixed-breed combinations have all been combined
into one category (mixed breed). Table IV compares pure breeds and mixed
breeds with respect to the total number and percentage of aggressive-behavior
problem types. Binomial tests indicated that the only individual problem
type which significantly differed between pure and mixed breeds was dominance
aggression (z = 2.95, P(one-tailed)= 0.0016), with dominance aggression
occurring more in pure than in mixed breeds. The difference for inter-male
aggression approached significance (z = 1.64, P (one-tailed) = 0.0505), with
inter-male aggression occurring more in mixed breeds than in pure breeds.