فصلنامه مدلسازی اقتصادی
سال شانزدهم شماره 4 (پیاپی 60، زمستان 1401)

Changes in taxes under different conditions of output growth can have completely different macroeconomic effects, and in this regard, some empirical evidence emphasizes the non-linearity and state-dependent effects of fiscal policy. This paper examines the state-dependent behavior of tax multiplier in Iran. Accordingly, a threshold model of specification presented by Romer and Romer (2010) is used to examine the coefficients related to the status of tax revenues to examine the effects of fiscal policies on output in the Iranian economy. The results of this study using quarterly data 1369: 02- 1398: 04 show that tax multiplier in low and medium regimes of economic growth is not significant. But the rising tax multiplier in a high-growth regime is quite significant. Also, increasing tax multiplier coefficients become smaller in periods of low economic growth, and these coefficients become larger in periods of high growth than in the entire sample period. Thus, tax policies in good times are quite effective tools, and the results emphasize the role of tax policies as a stabilizing tool by using the "right tool" at the "right time". Thus, although tax policies do not play an effective role during a recession, they can become a very effective tool for stabilizing and sustaining economic growth during a boom.

Estimating the amount of market power and determining the market structure of various industries is one of the most important topics in microeconomics,because the amount of production and price of various goods and services is affected by the degree of monopoly and market power of that industry.The purpose of this research is to estimate the degree of agreement and the levelof market power of the insurance industry using the Hall-Roger approach in the form of supply and demand equations with the help ofpanel data using the two-stage least squares method.For this purpose,the information of27public and private insurance companies In addition to the large share of their financial market in employment, the insurance industry is closely related to the characteristics of savings and the level of economic development of countries, and as one of the tools of risk management, it provides the expansion of social welfare on the one hand, and on the other hand It leads to the growth of investment and, as a result, more production and economic prosperity.As expected,the research results indicate the mutual dependence of insurance industry companiesSo that more than 85%of the investigated insurance companies have been able to enjoy a significant profit margin by creating a gap between the price and the final cost.Also the calculation results related to theLerner index based on theHall model show the information related to the coefficient of heterogeneity among insurance companies.Iran insurance has the highest Lerner index with a coefficient of0.565andAsia,Dana andPasargad insurances are in the next ranks with0.419,0.248and0.182respectively,

The purpose of this research is to calculate the distance to default of 14 banks admitted to the Tehran Stock Exchange and active in the banking industry of the Islamic Republic of Iran, based on the option pricing method of Merton, Black-Scholes, using the calculation of the market value of the banks' assets and their risk in the period The time is 1392-1400. For this purpose, the average market value of assets, liabilities and asset risk of banks and the distance to their default are calculated and compared.The index of distance to default of each of these banks in this period depends on the market value of assets, risk of assets, risk-free interest rate and debt. These variables depend on economic and non-economic and managerial factors. Bank Ansar, with the lowest average market value of assets, has the shortest distance to its default. On the other hand, Bank Mellat, which has the highest average market value of assets, has the longest distance to default. As a result, the most bank assets will have a longer distance to default.

This research mainly aims to investigate the effect of economic-social development on air quality in Middle East countries. For this purpose, the effects of Socio-economic Development indicators and natural resource utilization indicators are examined as one of the main drivers of growth and development in the Middle East on Sulfur dioxide  emission as an indicator  for air  quality. Since air pollution is a stable occurrence over time, the time-varying coefficient panel data model during the time period 2000-2019 is used to examine the impact of variables on Sulfur dioxide emissions. The results show that human capital, per capita income, and innovation have the greatest impact on the increase in Sulfur dioxide emissions, but resource usage indicators, especially the consumption of fossil fuels, lead to a decrease in Sulfur dioxide emissions. In fact, given the low use of renewable energy in the Middle East, energy consumption is mainly based on carbon sources. Thus, it is necessary to use environmental technologies and innovations instead of technology-based activities to control this issue in order to achieve sustainable economic growth and development.

This study investigates the determinants factors of systemic risk in Iranian banks during 2013-2022. The contribution is on banks liquidity creation and their balance sheet structure. For this purpose, the systemic risk of banks has been estimated and ranked by marginal expected shortfall (MES) index, using dynamic multi-garch models. The results by using Panel GMM method indicate that an increase in the balance sheet liquidity creation causes the vulnerability of banks to increase. Also, the liquidity creation on the side of assets (holding non-cash assets) significantly increases the systemic risk for banks, while which on the side of debts (holding of demand deposits) reduces the banks systemic risk and their fragility. In addition, the findings indicate that the bigger the size, the more non-traditional activities (non-interest income) and the higher the ratio of non-performance loans, the higher systemic risk in banks. while the higher capital adequacy in banks, the lower the systemic risk.

The purpose of this article is to evaluate the effects of information and communication technology on the quality of the environment (publication pollutant gases, carbon dioxide and greenhouse gases) and ecological footprint (from three aspects of the effect individual, country reserves trend and land type) in member countries of the Economic Co-operation and development  Organization is using the panel data method in the time period of 1992-2018.The results showed Expanding the use of ICT  in the mentioned countries has a positive effect on improving the quality of the environment And It has reduced the emission of carbon dioxide, greenhouse gases and ecological footprint.Furthermore, the consequences of ICT on the quality of the environment in the long term have been more than in the short term. Therefore, the findings showed that the substitution effect of ICT (substitution of online activities) compared to Income effect (increased leisure time from the substitution effect and increased travel demand) in the case study has been dominant.