رابطه فساد و توسعه اقتصادی : اختلاف در سطح درآمد در یک چارچوب غیر خطی

This article investigates the relationship between income and corruption which provides an insight to the changes in the level of perceived corruption and economic development across countries. An existing shortcoming is that previous studies have focused only on detecting the linear effects of income on corruption. We therefore use the hierarchical polynomial regression to evaluate any existence of a non-linear relationship after controlling for socio-economic and institutional factors. Our results challenge some of the findings of a negative income–corruption association in the literature, and provide some new inferences. The findings indicate a quadratic function that best fits the data, and despite an upsurge of corruption among the low-to-medium income countries, the advanced stages of development eventually reduce corruption level substantially. The results persist when per capita income is instrumented for by latitude distance and life expectancy. The policy implications suggest a combination of economic, institutional and social policies that can effectively, in turn, reduce and lower the effects of corruption on the society, economy and development.

It has been established that the impact of corruption is detrimental to all societies, which also explains poor economic performance especially in the context of developing economies.1Lambsdorff (2006) notes that cross-country empirical studies have explored the causes and effects of corruption since last decade, and some consensus has slowly emerged but a number of aspects still remain unresolved. Several studies highlight that prevalent corruption is negatively linked to the level of economic development of a country, hence rich countries (i.e. high per capita income nations) are perceived to be less corrupt than poor nations (i.e. low per capita income countries).2 However, such a stability or reduction in the perceived level of corruption was accompanied by significant rise in real income per capita. But it remains unclear whether an increase in income consistently reduces corruption across regions and income categorisation of countries. An important shortcoming has been that researchers' have focused only on detecting the linear effects of income on corruption. While the linear negative relationship between income level and corruption has been noted in the literature, however, the degree of the level of income impact on corruption is not uniform and straight forward. The overall long-term trend of the entire process may resemble the downward slope portrayed by a linear function, but the quadratic function can discriminate the experiences of less developed countries from that of the highly developed countries. Hence, a non-linear framework estimated in this paper explores the degree of responses of corrupt behaviour caused by the change in income level in a more systematic way. This focus provides an insight to the changes in the level of perceived corruption and economic development across countries. We question whether corruption levels increase or decrease in the course of a country's economic development and test the factors that determine the level and trends of perceived corruption.

This study provides strong evidence that corruption can be explained by various socio-economic, political and institutional factors and that there also exists a non-linear relationship between corruption and the level of economic development of the nations. The linear results show a strong negative nexus between income and corruption across countries. In addressing the level of how much improvement in corruption can countries expect from a higher income level, the estimated coefficients range from 0.876 to 1.321 indicating that an improvement of one standard deviation in real GDP per capita reduces corruption between 0.925 and 1.39 points. This association is robust after controlling for endogeneity bias. In spite of its role in controlling corruption, however the classification by regions shows that higher income does not appear to reduce corruption.