The apparent convergence of OECD income levels since 1950 is subjected to rigorous testing that suggests that there has occurred a systematic process of catching up in levels of total factor productivity. An econometric model of relative economic growth exhibits parameter stability over three...

Widely used 'purchasing power parity' comparisons of per capital GDP are not true quantity indexes and are subject to systematic substitution bias. This bias may distort measurement of convergence and divergence. Extending Hal R. Varian's nonparametric construction of a true index gives the set...