فصلنامه تحقیقات مدلسازی اقتصادی
سال یکم شماره 4 (تابستان 1390)

Value Added Tax (VAT) as a method of tax charging with creating a new tax base broad has been interest of many countries. Also Value Added Tax in our country in order to reform the structure of tax and increasing government revenues was approved by the House after a relatively long time and in the second quarter of year 1387 was carried out. Given that this law as an experiment and for five year was carried out study of effects of this tax on macroeconomic variables is of particular importance. In this study has tried to use the analytical relationships Input-Output and production of technical coefficient matrix constant assumption of fixed economic conditions and economic variables and limiting assumptions of this study to the price effects resulting from applying VAT on cost of whole different departments to deal with the country's economy. By using of model price of input - output and applying tax rates issue of Article 12 on exemption for goods and services and ultimately applying export exemption issue of Article 13 on value added tax the price effects of each section of economy is calculated and with and with considering of share of each section from the whole output the price effects is calculated. Results show that implementation of VAT has had very low price effects.

The Iranian electricity market is undergoing the first decade of restructuring. Effective competition in wholesale electricity market is a necessary feature of successful electricity industry restructuring. The paper examines the degree of competition in the Iranian electricity market during March to September 2009. The competitive benchmark analysis has been used to simulate producer’s behavior as a price taker firms and compare the competitive market results with actual market outcomes. The competitive benchmark has been calculated through generation costs of producers. Moreover, the possibility of execution market power has been considered by structural index. The finding indicates that the Iranian electricity market has a considerable potential to exercise power market and there were significant departure from competitive behavior during 2009.

This study tries to examine the way housing residential investment in Iran's urban area is influenced by the shocks of oil revenues, and for that, time series data spanning the period 1991:1-2007:4 are deployed in a Dynamic Stochastic General Equilibrium (DSGE) model including households, firms producing new residential houses, and the production of other economic firms as well as oil sector. The model is based on some simplify assumptions suitable to Iran's economy characteristics as: Iran as a small economy regarding capital flows, Oil Exports and goods imports and no price stickiness in housing sector. Moreover, the allocation of resources in the economy is determined by a central planning. The Model's solution and simulation is processed through using DYNARE as a subset of MATLAB software package. The results showed that the incidence of extreme volatility in the short behavior of housing residential investment in Iran's urban area, due to shocks of oil revenues, shocks was not Persistent and quickly disappeared. This implies that Iran's economy is suffering from Dutch Disease.

Monetary shocks are one of the control tools in economic systems. A true perception of these shocks on economic systems can lead us to a suitable policy. In this paper, the impact of monetary shocks on output in Iran has been modeled and investigated using artificial neural networks. We investigated positive and negative shocks separately and confirmed asymmetric effect of these shocks. In addition, nonlinear natures of output changes considering magnitude of shocks were obtained. Results show that optimal condition of monetary shocks to gain maximum output growth can be reached using artificial neural network. In other words, symmetric or asymmetric behavior of monetary shocks depends on economic situation in considered year or period. In addition to, investigation of monetary shocks effect (positive or negative impact) on the production changes, depending on the shock value and this shocks do not have an only particular Effect on production changes. Its can be different.

The optimal usage of oil as a natural resource is an important problem in exporting countries. These countries always are encountered with uncertainty and volatility of oil prices and its effects on real exchange rate. The main purpose of this paper is to investigate the relationship of between oil prices and exchange rate by emphasizing institutional quality in during 1995-2006. The model of this paper is estimated by panel data approach. Findings show that the oil prices have a positive effect on real exchange rate and it reduces international competition power. But institutional quality affects the extent to which the real exchange rates of oil-exporting countries co-move with the oil price. The results show that countries with high institutional quality such as control of corruption and regularity quality have real exchange rates which co-move less with the oil price.

With regard to importance of investment as an engine of economic growth many economists such as Wicksel, Keynse and Harrod believe that investment is the main source of business cycles. Hence this study specifies investment function according to a basic macroeconomic model such as Ramsey model. Application of Ramsey model can help to extend macroeconomics with micro foundations in economy of Iran and prepares new scopes for researchers. The main idea of this study is specification of investment function according to Ramsey model and its estimation by cointegration technique for period (1990:Q1-2007:Q4). The result of econometric estimation indicated a long run relationship between investment, capital stock, and shadow price of capital, installation cost of capital, capital price and terms of trade. Results showed that capital stock, shadow price of capital and terms of trade have direct effects and, installation cost of capital and capital price have inverse effect on investment.

Macroeconomic performance has improved in many countries in the world in the last fifteen years or so. Much of the literature has concentrated on how central bank independence, inflation targeting regimes, and currency unions have contributed to improving the effectiveness of monetary policy and hence macroeconomic performance. Since the financial system is a key component of the monetary transmission mechanism, we study how a country’s financial development affects monetary policy efficiency in 28 developed and developing countries within 1995-2006. Specifically, our objective is to derive monetary policy efficiency measures (PEMs) - derivative from Krause and Rioja- for 28 Developed and developing countries and analyze the impact that the size and depth of the banking sector and the capital sector have on policy performance. In our empirical analysis we use three financial development measures: private credit, liquid liabilities, and a financial aggregate index that comprises banking and stock market measures. The Results of model estimation with generalized method of moments (GMM) technique, shows that financial development with mentioned indicators has a positive and significant effect on monetary policy efficiency. Also supervision in central bank independency and inflation targeting regimes -as control variables- has positive and significant effect on monetary policy efficiency. This result doesn’t make a difference whether the country is developed or developing and in the both of them more developed financial markets, controlling the central bank independency and applying inflation targeting regimes, significantly help to achieve a more efficient monetary policy.

Increase in environmental pollutions of fossil fuels calls for policies stimulating clean technology deployment especially in the transportation sector. To evaluate the efficacy of these policies we should explore the preferences of consumers regarding different technologies. In this paper we use a discrete choice approach used in “Canadian Integrated Model system” (SIMS) to identify the behavioral components. This model has a hybrid top-down bottom-up structure. For this purpose we estimate a multi-nominal logit model (MNL) for different automobile technologies and different transportation modes based on preferences revealed by a sample of 250 Tehran citizens. Then, we evaluate the effects of economic, technological and environmental policies on market share of different automobile technologies and air pollution in Tehran. These policies include gasoline price increase, pollution tax, limitations on single passenger cars and limitations on use of gasoline driven cars. According to this analysis, technology based policies can effectively correct the market shares towards clean traffic technologies.