"Hyde and Mertz found there are more girls in the top tier in countries such as Iceland, Thailand, and the United Kingdom–and even in certain U.S. populations, such as Asian-Americans."<p>I don't buy this at all, if you mean "top tier" in the sense of people who are at the Olympiad/math professor level. Look at the numbers- there have been ten Fields/Abel/Wolf Prize winners from the UK, all of whom have been male. The odds of this happening given "more girls in the top tier" are less than 1:1000.<p>"Furthermore, they noted that a small math gender gap correlated with a higher rank on the World Economic Forum’s 2007 measures of gender equality, in which the United States ranked 31st, between Estonia and Kazakhstan. A similar correlation was found for the number of girls on International Mathematical Olympiad teams."<p>Yes, but <i>what was the correlation</i>? 0.02? 0.2? 0.9? The article doesn't tell you, conveniently for them.