More generally snkeaipg, in economies like (our TF2 one) with many, many items that are being traded, say N, there will be (N=1)N/2 relative prices should be (N-1)*N/2.A couple of questions:1) for the estimated price of hats in terms of keys, you're weighting the sum by the number of times the things are traded. Is there a particular reason you weight it like this and not with some other data instead of times traded? I'm guessing you're assuming items that are traded more often are nearer to their equilibrium price? If that is so, do you think, after doing all this analysis, that such an assumption is reasonable for the TF2 economy?2) This is more of a general economics question since I'm not an economist to calculate the index of arbitrage potential, you use the sum of least squares. Do economists ever use other distance functions to measure such an index? If so, is there anywhere I could read more about it?