To the Editors (Caleb Pomeroy writes):
In “The Power of Nations: Measuring What Matters,” Michael Beckley persuasively argues that aggregate measures of power systematically exaggerate the capabilities of relatively populous countries.1 Traditional measures of capabilities—namely gross domestic product (GDP) and Composite Index of National Capability (CINC) scores—fail to deduct state liabilities, including production, welfare, and security costs. Beckley's proposed solution is to replace measures of aggregate capabilities with a measure of GDP multiplied by GDP per capita (GDP × GDPPC), thus penalizing countries with large populations. The variable exhibits strong theoretical appeal and case-level evidence. For quantitative international relations scholars, however, the most convincing argument for the adoption of this variable hails from the variable's model fit improvements in the “majority of studies published in leading journals over the past five years,” as noted in the article's summary. I raise two issues with such a claim.
First, the...