Per capita spending is a little misleading here, is it not? Ceteris paribus, http://www.novinite.com/articles/143867/Bulgarian+Teachers+w... suggests Romania gets Bulgaria's educational results at nine tenths the cost, and Bulgaria achieves Luxembourg's results at a[n adjusted] seventh of the cost. I have no doubt that adjusting for teacher salaries leaves the rest of your analysis in tact, but I imagine the process would be educational in itself.