AIC (Akaike Information Criterion) ranks competing models by balancing how well they fit the data against how many parameters they use — simpler models are rewarded. Lower AIC = better model. Unlike R², AIC is useful for comparing models even when none fits well: it tells you which is the least bad option. The power law wins on both R² and AIC vs the traditional quadratic Armey Curve across the 113-country structural sample.