خلاصة:
The underground economy has long been of interest to economists and has devoted extensive studies to itself in economic literature. Through fuzzy logic approach in present research, we estimated the size of underground economy of Iran over the period of 1978-2010. For this purpose and according to theoretical bases and previous studies, variables such as GDP per capita, ratio of direct taxes to GDP and an index of business environment for considering the effect of institutional structures have been used as the most important explanatory variables for estimating country's underground economy. For considering the quality of institutions in this research we have used a local index for the first time compared with other internal studies. Our results indicate an oscillatory trend as the average of relative and absolute size of underground economy has decreased during the years of first development plan compared with period of war and revolution but increased during the second plan compared with the first one. Also it has decreased over the years of third plan in comparison with the second one but again it has increased during the fourth development plan. According to the results, the average of relative size of underground economy to official output during the years of war and revolution, first, second, third and the fourth development plan was approximately estimated 21, 12, 29, 19 and 20 percent respectively. During the entire period it was approximately 20 percent.
ملخص الجهاز:
For thispurpose and according to theoretical bases and previous studies,variables such as GDP per capita, ratio of direct taxes to GDP and anindex of business environment for considering the effect of institutionalstructures have been used as the most important explanatory variablesfor estimating country's underground economy.
According to the results, the average of relative size of undergroundeconomy to official output during the years of war and revolution, first,second, third and the fourth development plan was approximatelyestimated 21, 12, 29, 19 and 20 percent respectively.
This study estimates the size of the underground economy in Iran with respect to the most important variables including an index for the business space, the share of direct taxes in production and per capita production.
Arabmazar Yazdi (2001) estimated the relative size of the underground economy during years 1968-98 through MIMIC method, using the direct tax burden, the burden of taxes on imports, growth in consumer prices, unemployment, an index for economic openness and per capita income as explanatory variables, equal to 11 percent.
Based on the results, the average relative size of the underground economy during the mentioned period is estimated equal to 14 percent of the official production.
5. Estimation of underground economy volume As discussed above, in the present study, using three input variables, direct taxes to gross domestic product ratio, per capita production and an indicator of business environment in Iran, the volume of the underground economy for years 1978-2010 has been estimated.