A useful study that has taken into account those that have been convicted of the crime itself. The study would have been useless had it ignored the criminal element and only presented finding from the lawful side of society.
Also the 40 year period of data expands the usefulness of the study.
This podcast turned me into a zoo ally. It's funny, quirky, and informative. They always have something new to talk about. The podcast does a great job at uniting zoos, and it will often feature guest appearances from the community. Just give it a listen and see how you like it!