What dog breeds score highest in a tendency to show aggression toward strangers? To other dogs? To their owners? And are factors other than breed more or less important in evaluating a dog's potential for aggressive behavior?

While there is no single scientific study that has definitive answers to these questions, the peer-reviewed journal Applied Animal Behaviour Science has made "Breed Differences in Canine Aggression" (2008) available free in its entirety on Science Direct.

The study's authors examine data from their own research, for which they surveyed owners of more than 30 breeds of dog using the Canine
Behavioral Assessment and Research Questionnaire (C-BARQ). They also provide an overview of data from other studies on the same topic.

The complete study can be viewed here.