As seen in Table 5, 267 of the 1,806 herding dogs described participated in working dog trials. Forty-three of these dogs were used only for trials. The remaining 84% performed herding work outside of competitions. Dogs competing in working dog trials had a significantly greater chance of falling into the group of respondents reporting average or above-average success rates. (Retrieved from:http://journals.plos...al.pone.0104457)
ETA: I do not mean to suggest this was the focus of the study; it is just one factor. I was not clear with my post title that this was just one takeaway from the study.