This paper comparatively investigates different effects of improving economic and political institutions on per capita income in the countries whose institutional performance is evaluated either ideal or else. For this purpose, this study applies econometric analysis of cross-sectional data. In the econometric approach, the effect of improving institutions on per capita income of G20 countries is compared with that of oil-exporting countries. The results show that the effect of improving institutions on per capita income in oil exporting countries with low institutional performance is greater than that in G20 countries, where the institutional performance is visibly good. Hence, the constitutional law executives in oil exporting countries should try to improve their economic and political institutional arrangements more robustly than those in industrial states.
