Cross-cultural analysis is all about comparing groups. Whether the groups being compared are countries, ethnicities, religions, or scientific fields, the goal is always to assess whether these groups differ in some respect and to interpret those differences in substantive terms. For example, political scientists may be interested in cross-country differences in “internal political efficacy,” the public’s feeling that they are personally capable of influencing politics (Coleman & Davis, 1976). Healthy democracies are thought to need high levels of this feeling (Wright, 1981), and it may be of interest to examine why some countries have more of it than others; Karp and Banducci (2008), for instance, argued that proportional versus majoritarian election systems explain some of these cross-country differences. Other comparisons of substantive interest might regard the link between efficacy and voting: What differences are there across countries in the strength of this link, and how can we explain those differences?.