The researchers, noted, however, that the math gap wasn't consistent between countries. For example, it was nearly twice as large as the [US?] average in Turkey, while Icelandic girls outscored males by roughly 2 percent. The general pattern of these differences suggested to the authors that the performance differences correlated with the status of women. The authors of the study built a composite score that reflected the gender equality of the countries based on the World Economic Forum's Gender Gap Index, data extracted from the World Values Surveys, measures of female political participation, and measures of the economic significance of females. countries such as Norway and Sweden score very high on gender equality measures; in these nations, the gender gap on math performance is extremely small.