The study looked at differences in personalities via interviews of men and women, not at the types of choices they made. So, for example, in more equal countri

The study looked at differences in personalities via interviews of men and women, not at the types of choices they made. So, for example, in more equal countries there is a higher gender difference in trust and altruism than in less equal countries. For the countries, they categorised them on a few factors: "we created a Gender Equality Index as a joint measure of four indices of gender equality: (i) the Global Gender Gap Index of the World Economic Forum (WEF), (ii) the Gender Equality Index of the United Nations (UN), (iii) the ratio of female to male labor force participation rates, and (iv) the number of years since women’s suffrage."