Leave it to an Ivy leauge school to conduct a study on what everyone already knows
Wonder how the numbers turn out if you run groups of refs thru the same sessions?
Which is another factor/question in the whole dirty vs. hard story
Do some schools/coaches push the players to play to the whistle (foul type)/yellow card and then to back down after the refs show a lack of tolerance for that type of play, and of course if he refs lets it go then the coches/players play harder trying to find the limit?