That is no sort of study. Yes, there is plainly a difference. Quite an astonishing one. Well and good. But if you're trying to do any sort of actual analysis, you can't just offer theories, list a few pros and cons, and choose one as explaining reality. You have to demonstrate why, with data, that theory is the best available. Nothing, NOT ONE THING, is done to substantiate the claim that the reason for the different is that the cost of farming gold must be cheaper on EU servers, nor is anything done to substantiate the second-order claim that this is due to differences in how they police the respective server-zones.