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Contradicting this assertion, the Wisconsin researchers show that girls' math scores are as variable as boys' in some countries and among some ethnic groups in the U.S., with as many girls as boys scoring above the 99th percentile in some cultures. Thus, greater male variability in math performance is not a ubiquitous phenomenon.

Having read the article, I think this point was well-supported.

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Rather, Hyde and Mertz report that the ratio of girls to boys excelling in math correlates quite well with measures of a country's gender equity.

This claim appeared weaker. One of the countries where the number of math-gifted girls equalled or surpassed boys was Thailand, which I wouldn't consider a bastion of feminism. But I don't even really care if this one is strictly true, because the prior claim is what interests me more.