Investigating the Effect of Fluctuations of Macroeconomic Variables on the Gini Coefficient of Income Deciles in Iran with Fuzzy Regression Approach

The uncertainty of macroeconomic variables imposes irreversible effects on economic phenomena. Therefore, it is necessary to avoid the effects of uncertainty on macroeconomic variables. One of these phenomena is income inequality. Hence, investigating the effect of macro variables uncertainty on income distribution requires careful modeling. In this paper, using the fuzzy regression model with symmetric and asymmetric coefficients in MATLAB and GSM program environment, we investigate the uncertainty of macroeconomic variables on Gini coefficient of income deciles in Iran for the period 1995-2007. . The results show that the Gini coefficient of the right and left widths of all income deciles except for the second and eighth deciles did not fluctuate significantly until 2011. The increase in the fluctuation of the right-income declining amplitude of the second decile indicates the inequality and the effectiveness of this decile due to the uncertainty of the large variables. The dramatic decline in the amplitude of the 8th Right Decade Width fluctuation in 2009 is due to economic developments and improved income distribution. Also, the increase in the amplitude of the right and left Gini coefficients of income deciles, especially the upper deciles in the years after 1390, indicates an increase in inequality in the income distribution in these years. As such, this inequality is more severe in the tenth income deciles, which makes the rich richer. The most common criteria for MSE, RMSE, MAPE, MAE are used to evaluate the results, which shows the excellent performance of fuzzy coefficient regression model.