mixed data sampling model

A high national savings rate leads to more investment in a nation's capital stock, which can increase productivity and economic growth over the long run. Therefore, identifying factors affecting national savings has particular importance. Income inequality is one of the influential factors impacting national savings. According to that, the current research has investigated the effect of income inequality on the national savings of Iran for the period of 1989-2020 by using the mixed data sampling approach. The findings of the research shows that income inequality has a hump-shaped effect on national savings. So, at low levels of inequality, the quantity of savings increases due to the transfer of income from the poor to the rich that have a high marginal propensity to save. But, after reach to a certain level of inequality, a more increase in inequality along with the country's economic situation (inflation, widespread sanctions, and the firm's economic recession) causes a decrease in employment and wages, which is associated with an increase in the number of poor in the society. The impact of the reduction in the poor's savings overcomes the influence of an increase in the rich's savings as the number of poor increases. Therefore, more increases in income inequality lead to a decrease in national savings. Also, variables of economic growth, real interest rate, and trade have a positive and significant effect on national savings. But variables of dependency burden, the effect of wealth, financial development, and economic sanctions have a negative and significant impact on national savings.

The present study intends to use the Mixed Data Sampling model (MIDAS) to investigate the effect of exchange rate changes on the variable of real production in Iran during the period 1397:1  to1380:4  that Provides implement a flexibility model whit  high descriptive power, including variables of varying frequency (eg daily, weekly and monthly) together in a regression.The results of this study show that the MIDAS model is statistically strong in identifying the asymmetric dynamic effects of the independent variable with higher freuency (exchange rate changes) on the dependent variable with lower frequency (GDP) compared to the same frequency model of these variables and shows asymmetry better.Also, based on the obtained results, the intensity of the impact of the momentum and the persistence of each momentum are different, so that the negative momentum of the exchange rate has more intense and lasting effects on Iran's GDP.