سید کمیل طیبی

Exchange rate reforms in developing countries have often aim to floating the exchange rate to unify official and parallel foreign exchange markets. The present study has examined the dynamic effects associated with such reforms, focusing on the exchange rate unification policy and its impact on the import price index of capital goods during the years 1978–2022. For this purpose, the variables affecting the import price index have been first identified using the Time-Varying Parameters Dynamic Model Averaging (TVP_DMA) framework. Then, the Time-Varying Parameter Vector Autoregression (TVP-VAR) model has been used to analyze how the import price index is affected by the exchange rate unification shock.  According to the empirical findings, the variables of economic growth, the exchange market pressure index, the import dependency ratio, trade tariffs, and the exchange rate unification index are among the most influential factors affecting the import price index of capital goods in Iran. The import price index of capital goods has exhibited varying responses to shocks arising from exchange rate unification policies, depending on the prevailing economic conditions of the country. The magnitude of this impact has fluctuated across different periods; specifically, heightened economic instability has increased the sensitivity of the capital goods price index to changes in the exchange rate unification index. This effect became more pronounced during the 2010s. particularly at the beginning and end of the decade, when the national economy was heavily influenced by external factors and exceptional circumstances. As pressures on various economic sectors intensified during this era, the response of the import price index of capital goods to the gap between official and informal exchange rates became significantly more severe than in other periods. Consequently, these conditions led to a situation where shocks from exchange rate unification policies resulted in a sharp surge in the import price index of capital goods.

This paper addresses the strategic optimization of renewable energy integration into Iran’s electricity generation portfolio over a 25-year period, leveraging the computational strength of genetic algorithms. With an energy sector heavily reliant on fossil fuels, Iran faces increasing pressure to diversify its energy sources in light of global environmental commitments and domestic sustainability challenges. The study introduces a multi-objective optimization model that minimizes environmental pollution and economic costs while considering technical and policy constraints. The model simulates and predicts optimal shares of various energy sources including fossil, nuclear, solar, wind, hydro, biomass, and geothermal, offering a forward-looking investment prioritization strategy for national energy planning. The primary objective of this study is to design an optimal mix of energy sources for electricity generation in Iran that reduces reliance on fossil fuels while maintaining economic feasibility and environmental responsibility. It seeks to answer two main policy questions: (1) What should be the optimal share of renewables in Iran’s electricity generation mix and (2) At what rate should the transition from fossil fuels to renewables be implemented over a 25-year horizon 

Optimization in mathematics means finding the optimal values ​​of a function. Energy consumption optimization can be performed locally or comprehensively for a system consisting of several processes. Comprehensive optimization is more complex than the local method due to the need to understand the energy dynamics of the equipment. Optimization methods are also divided into three categories based on cost: low-cost, medium-cost, and high-cost. Classical optimization methods are suitable for those problems that have multiple and implicit objective functions of decision variables, and for solving large-scale problems and mixed-optimization problems, classical methods are difficult and sometimes impossible; for this class of problems, meta-heuristic and intelligent stochastic methods have been developed that use the principles of natural phenomena and enable them to explore large search spaces and identify optimal solutions effectively. Given that the research problem is a multi-objective, multi-variable, constrained, dynamic, stochastic, convex, nonlinear, and continuous problem; Metaheuristic evolutionary methods are the most appropriate method for solving it. Among these methods, the genetic algorithm has been introduced as one of the most well-known and widely used evolutionary algorithms. This algorithm gradually evolves the population of solutions by using biological concepts such as inheritance, selection, and mutation and guides it towards optimal values. Considering that the problem of the present research is multi-objective, constrained, dynamic, and nonlinear, the use of evolutionary methods, and especially the genetic algorithm, is considered the most appropriate approach to solve it. In order to optimize Iran's energy production portfolio, a combination of optimal production sources is considered that has lower pollution and cost. This goal can be evaluated in two ways; one separately and the other combined. In other words, the optimization goals, which are to minimize pollution and energy production costs, can be modeled in two separate functions or considered in a combined function. By separately stating the goals, it is possible to find solutions in which even one of the criteria is optimal, and by applying the resulting weight, the optimal solution can be obtained under any conditions. 

The optimized energy mix demonstrates a substantial shift from the current structure. The share of fossil fuels in electricity generation drops from 92.4% to about 55.4%, while renewable sources (especially solar and wind) and nuclear energy see significant growth. The forecasted production for 25 years ahead shows that renewable energy, particularly solar, becomes the dominant source of new energy capacity additions. The model predicts that investment in fossil fuel-based electricity should be minimized and existing capacities should only be maintained rather than expanded. This shift meets both environmental goals and supports Iran’s energy security in the long term. 

Iran’s current electricity generation mix is suboptimal from both economic and environmental perspectives. This study provides a robust quantitative framework using genetic algorithms for forecasting and optimizing energy policy decisions. The results advocate for a strategic pivot toward renewables, especially solar and nuclear energy, over the next two and a half decades. Policymakers are urged to redirect capital investments accordingly and align energy planning with global sustainability targets. The methodology also allows for adaptability in future scenarios, supporting more resilient and responsive energy strategies.

A significant deviation of the official exchange rate from the market exchange rate is indicative of fundamental problems in macroeconomic policies and underlying imbalances in the economy. Maintaining a fixed exchange rate policy is neither sustained nor stable and leads to a range of distortions in the economy, which results in a lower growth rate in GDP. Given this, this study has investigated the Effect of the Official and Unofficial Exchange Rate Market Gap Shock on the Import Price Index of Consumer Goods (Exchange Rate Pass-through Approach) in Iran from 1979 to 2022. To this end, the study first identifies the most significant determinants of the consumer price index of imported goods using a Time-Varying Parameters Dynamic Model Averaging (TVP_DMA). Subsequently, the Effects of the Official and Unofficial Exchange Rate Market Gap Shock on the Import Price Index of Consumer Goods has been evaluated using a Time-Varying Parameter Vector-Autoregression (TVP-VAR) model. Based on the results, the Official and Unofficial Exchange Rate Market Gap Shock initially led to a significant increase in the Import Price Index of Consumer Goods. This effect was particularly pronounced during periods of economic instability. However, in the long run, the Effects on the Import Price Index of Consumer Goods has diminished. Accordingly, it is recommended that policymakers reduce the Official and Unofficial Exchange Rate Market Gap and implement stabilization policies to prevent excessive fluctuations and mitigate inflationary pressures on the Import Price Index of Consumer Goods.

Most of the countries using complicated multiple rate systems have been subject to inflationary pressures and to a more or less rapid rise in domestic costs and prices. Such an environment greatly complicates any exchange policy, because the exchange rate has to be adjusted frequently to keep an appropriate relation between domestic and external costs and prices. Considering this, the present study examines the effects of exchange rate unification policy on the aggregate import price index from 1979 to 2023. For this purpose, the most influential variables affecting the aggregate import price index are first identified using the Time-Varying Parameters Dynamic Model Averaging (TVP_DMA) framework. Subsequently, Then, the impacts of exchange rate unification shocks on the aggregate import price index are examined within the time-varying parameter vector autoregression (TVP-VAR) model. The results indicate that exchange rate unification leads to an increase in the aggregate import price index, with significant short-term effects that gradually diminish over the long term. Additionally, higher instability in the foreign exchange market causes the nature of the impacts (both in terms of intensity and duration) on the aggregate import price index to differ compared to other periods.Keywords: Multiple Exchange Rates, Unification, The Aggregate Import Price Index, Shock, The Exchange Rate Pass-through.

Exploring effects of the main determinants on exchange rate pass through is crucial for the adoption of various economic policies, including exchange rate stability as well as trade expansion. An exchange rate regime can be a source of exchange rate and price changes, which is substantial in the implementation of foreign exchange policies. Among the various factors affecting exchange rate pass through, the flexibility of exchange rate regime has received less attention in empirical studies. Accordingly, the present paper seeks to find out how different exchange rate regimes affect the exchange rate pass through, which is proxied by the import price. To answer this question, we have used the multiple-doses matching approach by estimating the dose-response functions, to evaluate the effect of an exchange rate regime on the pass through. To this purpose, we have used data of 118 developing countries employing four types of exchange rate regimes in 2021. The results obtained from the use of dose-response analysis show that there is a negative and significant relationship between the degree of exchange rate pass-through and the degree of flexibility of the exchange rate regime  at the significance level of 5%, so that an increase in the flexibility of the exchange rate regime has resulted a decrease in the degree of exchange rate pass-through. As a result, the degree of exchange rate pass-through in the hard-pegged exchange rate regime has been higher than those of other regimes, while, it has been the lowest in the floating exchange rate regime.

This statement that "capital is the most important driving force for growth and subsequent economic development in countries" can be considered universally accepted by all economists (regardless of economic school of thought). As a result, all models of growth and economic development have been developed based on the accumulation of capital. Therefore, this question arises: How is it possible to strengthen the production structure and apply advanced technologies in countries that are facing a lack of capital In this regard, researchers have shown great interest in foreign direct investment as a cover for the lack of capital in countries. Foreign direct investment is a type of investment that includes long-term relationships in which an economic unit in one country controls and benefits from a business unit in another country. Various studies indicate that successful countries in attracting FDI can provide the necessary conditions for positive future for multinational companies (as the most important players in the field of foreign direct investment). Furthermore, one of the main motivations for developing countries to attract foreign direct investment is mentioned as transferring and acquiring the necessary technologies to improve the productivity of domestic enterprises.   However, what leads to the attraction of this type of investment in developing countries (as the main applicants for capital and technological inputs) has always been a challenging issue. Some thinkers mainly focus on economic variables (such as economic openness, infrastructure availability, developed financial markets, etc.), while others do not find them sufficient and rely on non-economic factors, mainly derived from political science and international relations. According to them, the economic actions of individuals and companies are influenced by international political alignments, and therefore achieving economic development is only possible within this framework. This issue has become important in recent years with the popularization of the use of sanctions (meaning the use of economic tools to change the political behavior of a country) among the great economic powers.

Fluctuations and instability in key economic variables, including economic growth, productivity, international trade, prices, and government expenditure, can lead to deviations of the real exchange rate from its equilibrium level. Furthermore, external factors such as multi-rate currency systems and financial sanctions can exacerbate these deviations. These exchange rate misalignments exert significant impacts on investment, economic growth and development, trade flows, balance of payments equilibrium, optimal resource allocation, and other crucial economic variables and indicators. Given the historical prevalence of exchange rate fluctuations within the Iranian economy and the profound impact of these deviations on the country's economic performance, this study investigates the determinants of the real exchange rate and the mechanisms through which deviations arise. Subsequently, it examines the potential impact of exchange rate policies, specifically exchange rate unification, on mitigating these deviations from the equilibrium level. To this end, utilizing time series data on key macroeconomic variables spanning the period from 1975 to 2020, an empirical model of real exchange rate deviation is estimated employing the Vector Autoregression (VAR) method. The empirical findings demonstrate a significant response of exchange rate deviations to the implementation of exchange rate policies, particularly through exchange rate unification or improvements in institutional quality within the specified timeframe. The overall results suggest that an optimal exchange rate policy, achieved through exchange rate unification, contributes to dampening real exchange rate deviations and fostering greater exchange rate stability.

Considering the challenge of lack of capital accumulation and access to advanced technologies, foreign direct investment (FDI) is considered an important tool for economic growth in developing countries. Therefore, it seems very necessary to investigate the factors affecting its attraction to them. The attraction of foreign direct investment by any country requires the provision of a suitable environment in the destination country. On the other hand, the composition of the country's exports can indicate the quality of economic institutions in a country. So, the main purpose of this research is to investigate the effect of the composition of the country's exports on the attraction of FDI in developing countries.For this purpose, using gravity model and Panel ARDL, the effect of the export ratio of developing countries, based on BEC's classification, evaluated on the accumulation of foreign direct investment made by member countries of Group 7 during the years 2006 to 2019.The findings of the research indicate that the effect of changing the ratio of export of intermediate goods, capital goods and consumer goods has become significant in attracting foreign direct investment. While the change in raw material export ratio has had not a significant effect on the discussed variable. Therefore, adopting export facilitation policies and at the same time avoiding from raw material exporting is effective in attracting foreign direct investment.

Estimating the real exchange rate misalignment from the equilibrium value and exploring the factors affecting its changes is crucial for both economic policymakers and economic agents. Among the various factors affecting exchange rate misalignment, the exchange rate regime, has received less attention in experimental studies. Accordingly, the present paper seeks to find out the answer to the question of how real exchange rate misalignment is affected by different exchange rate regimes. In other words, in which of the exchange rate regimes is the exchange rate misalignment less and in which one it is higher To answer the question, the propensity score matching approach has been used. For this purpose, we have used data from 116 developing countries with different exchange rate regimes in 2019. Other factors such as real exchange rate misalignment in the previous period, inflation, the quality of institutions and financial development have been considered as match variables to net the effect of the exchange rate regime on real exchange rate misalignment and to separate the effects of other variables. The results showed that the real exchange rate misalignment from its equilibrium level has responded significantly to the type of exchange rate regime adopted by the countries, so that the floating exchange rate regime increases the real exchange rate misalignment in the selected developing countries wherever implemented. It can be argued that factors such as high exchange rate  fluctuations, a more drastic adjustment in the price level, and speculative bubbles or contagion effects in the floating exchange rate regime have led to an increase in these misalignments.

Due to the increasing growth rate of electricity demand as well as relevant supply challenges, the economic issues of power systems have been considered by governments and energy experts to achieve further efficient resources allocation. Based on an approach of a dynamic system, the aim of this study has been to modelling the regional integration of electricity markets among the selected ECO member countries (including Iran, Turkey, Azerbaijan, Pakistan and Afghanistan) in order to maximize the stability of electricity supply. Accordingly, the required data have been applied during the period of 1980-2019. In this respect, two scenarios, namely a scenario of self-sufficiency of electricity (implying national electricity market) and a scenario of free regional market (implying regional integration market) have been conducted respectively, by specifying and estimating a Structural time series model, to simulate the trade flows of electricity in the selected ECO country members by 2030. The simulated results have indicated that Iran has had the marginal storage of more than one and the lowest price among the countries, while it has the largest volumes of electricity exports. Afghanistan with the marginal storage of less than one among the regional countries has had the lowest volumes of electricity Imports. In addition, the empirical results have revealed the fact that the electricity price has been decreasing as a result of a decrease in the electricity production costs. Consequently, the paper findings imply that uncertainty in the electricity supply can be reduced through implementing an integrated regional electricity market among the ECO members.

The purpose of this paper is to specify an early warning system for currency crisis and to investigate the role of capital control together with other warning indicators in the crisis. Increasing mobility of capital and liberalization in international financial flows is one of important dimensions of globalization, which has significant benefits to many countries worldwide. However, due to negative impacts on exchange rates as well as currency crises, financial liberalizations followed by some Latin American and Southeast Asian countries raised concerns in the last decade of the twentieth century. Hence the question: can capital control play a role in preventing or exacerbating the currency crisis This study evaluates the relationship between capital control index and currency crisis and also examines the role of this variable as a warning indicator. Since the main application of the early warning systems is crisis forecasting, the purpose is to model the early warning indicators of currency crisis using Bayesian averaging method. To achieve this, 70 variables were examined for 60 countries during the period 1975-2019, both in floating and non-floating exchange rate systems. The results showed that capital control has a significant effect on reducing the occurrence of currency crisis, also different capital control indicators do not have the same warning power. In addition, different currency systems are effective in changing the power and rank of warning variables, especially for the use of capital control index.

This paper investigates the factors affecting export diversification in Iran. As deducted from heterogeneous trade theory, the main variables of interest in this paper's baseline specification are entry and trade costs. For this purpose, Theil index is calculated for export diversification.  This index is obtained for ten selected two-digit commodity codes in the HS coordinate system.  Then the basic model is introduced and estimated by the generalized least squares (GLS) method. Estimated results show that diversification depends negatively on domestic and foreign market entry costs. Therefore, reducing the unnecessary rules for setting up enterprises, customs regulations, creating transportation and financial facilities can help to improve the Iran's export diversification.

Exploring effects of the main determinants of exchange rate pass through is crucial for the adoption of various economic policies, including currency and trade policies. The exchange rate regime of countries is the source of exchange rate and price changes and is substantial in the implementation of foreign exchange policies. Among the various factors affecting exchange rate pass through, an exchange rate regime has received less attention in empirical studies. Accordingly, the present paper seeks to find out how the exchange rate pass through, which is proxied as the import price, is affected by different exchange rate regimes. To answer the question, we have used the propensity score matching approach, which is considered as a non-parametric method, to investigate the effect of an exchange rate regime on the exchange rate pass through, while other effective factors are controlled. To this purpose, we have used data of 118 developing countries with different exchange rate regimes in 2019. To evaluate the marginal effect of the exchange rate regime on exchange rate pass through, we have modeled the exchange rate pass through by including other match variables such as the nominal exchange rate, marginal cost of exporters, real GDP growth, trade openness, liquidity growth and inflation. The empirical results showed that the exchange rate pass through has responded significantly to the selection of an appropriate exchange rate regime, so that the adoption of the floating exchange rate regime reduces the degree of exchange rate pass among the counties wherever implemented.

Real exchange rate misalignment from its equilibrium level can have negative effect on economies worldwide, especially on developing countries. For this reason, it is important to economic policymakers to make attempts in order to control for any misalignment. As detection of the real exchange rate is a first step to control for its misalignments, this study has explored the effects of the main determinants on real exchange rate within a framework of a non-linear model using data of 120 developing countries over the period 2000-2019. The model, which was specified as a panel smooth transition regression, contained a set of explanatory variables such as productivity index, the ratio of investment to GDP, the ratio of government spending to GDP, trade openness, term of trade and net foreign assets. The empirical results indicated that changes in all aforementioned explanatory variables affected significantly the countries` exchange rates. In addition, the results revealed that existence of various types of exchange rate misalignments, like over/under- valuation of exchange rate, in most countries during the period, even those the intensity of misalignments were different in the countries under consideration. Among them, Iran experienced the vast fluctuations in the real exchange rate by 2002, while the less deviation from the equilibrium rate happened in the rest of the period. The reason for such misalignment has been typically based on the overvaluation and undervaluation of the domestic currency.

Terms of trade is one of the most important tools using for analyzing macroeconomic problems because, during time, it is a good criteria for assessing a country’s profit from international trade and its changes have direct effects on countries’ welfare.Besides, unification of exchange rate is an important issue in economical policies Considering the impact of exchange rate changes on terms of trade as well as to the terms of the importance of exchange rate unification policy,the purpose of this study is to analyze the effect of exchange rate unification on the terms of trade in Iran during the years 1991-2015. For this purpose, the structural vector autoregression (SVAR) model is used. Results of structural vector auto regressive model for Iran’s economy during the period under reviewsuggest that exchange rate unification destroys the trade relationship in the short run but improves in the long run. If the rate of exchange rate unification is higher, it will have a greater effect on the trade relationship.

According to the Heckscher-Ohlin-Vanek (HOV) theory, besides labor force and capital other production factors such as energy and indicators of environment quality may affect exporting potentials of goods and services in an economy. Accordingly, the objective of this paper is to explore the effects of the main determinants, particularly carbon dioxide emission intensity, which is a proxy for environment quality, on the net exports of the selected manufacturing products (auto parts and petrochemical products) between Iran and its major trading partners. Basically, an econometric model for Iran’s net exports is applied to these trading products specifying two panel regression equations using the data of 21 Iran’s partners over 2000-2019. Empirical results have been obtained by estimating two regression equations of auto parts and petrochemical products net exports using panel GLS method. Based on the empirical results, there is a significant and negative effect of the ratio of Iran’s carbon dioxide intensity to that of its trading partner on net exports of auto parts, which implies a decrease in the trade deficit of these products. In contrast, the results show that the environmental quality significantly and negatively affects the net exports of the petrochemical products implying a rise in the ratio of Iran’s carbon dioxide intensity to that of its trading partner, which decreases Iran’s net exports of the petrochemical products.

Propensity score matching is extensively utilized in estimating the effects of policy interventions and programs for data observations. This method compares two treatment and control groups to make statistical inferences about the significance of the effects of these policies on target variables. Therefore, when using propensity score matching, it is significant to obtain the standard error to estimate the treatment effect. The precise estimations of variance and standard deviation facilitate more efficient statistical testing and more accurate confidence intervals. However, there is no agreement in the literature on the estimation method of standard error; some methods rely on resampling, while others do not. This study compares these methods using Monte Carlo simulation and calculating the Mean Squared Errors (MSE) of these estimators. Our results indicate that Jackknife and standard methods are superior to Abadie and Imbens (2006) bootstrap, and subsampling ones in terms of accuracy. Finally, reviewing Tayyebi et al. (2019) indicated that different methods of estimating variance in the matching estimator led to different statistical inferences in terms of statistical significance.

In this study, we simulated the effect of trade on Iran's economic growth by using a combination of econometric methods and system dynamics. Through the design of a conceptual framework, an attempt has been made to expand the Ozawa (1965) -Lucas (1988) growth pattern by expanding the Oniki-Ozawa (2015) model. Entering the role of trade through trade volume and foreign investment inthe model, we simulated and predicted  the effect of these two factors on the trend of production of goods and knowledge production, human capital index, and innovation indexfor the period of 1359 to 1409 (Solar Year). We used business data from Malaysia and Turkey to analyze a shock and compare the result  with Iran's data. The results show that the effect of technology resulting from trade (in the sense of foreign investment) only affecte the  technology function, and the growth of technology has  a positive effect on the knowledge production function. In addition, trade has not a positive effect on the commodity production function.. Besides, following Malaysia’s trend of foreign investment to simulate Iran’s situation  is beteer working than the model of Turkey and current Iran’s model. Finally, the result of forecast for economic growth for the period of 1399 to 1409 indicates a situation of economic recession. With countinuing this situation and sanction, a worst situation is expected. 

Due to the fundamental differences in technology, factor abundance, labor productivity and economic capacities, developing countries need to attract FDI in order to achieve sustainable development goals. FDI transfers a variety of spillover effects including advanced technology, modern management and productive capital which properly help saving and promoting the environment. Indeed, FDI develops economic potentials of developing countries to expand export markets and to participate in the global economy, a fact that quantitative values lead to qualitative ones. Now, the question arises whether attracting any kind of FDI by emerging and developing economies leads to high-value employment opportunities, or preserves the environment. Do sustainable FDI flows secure sustainable development goals in developing countries The basic hypothesis of this study is based on assessing the validity of this claim, subject to being empirically tested. This study investigates the effect of FDI on the sustainable development process in selected developing economies by using a panel data model over the period 2000-2018. The results indicate the significant effect of FDI and its spillover on sustainable development of selected countries. However, environmental pollution has statistically a negative and significant effect on sustainable development in these countries. The negative interaction effect of FDI and carbon dioxide emission on sustainable development indicates that if FDI triggers environmental pollution in host countries, it will hinders the path to sustainable development.

Intra-industry trade (IIT) in final goods, which depends on transport costs, seasonal trade and even product diversification, is often subject to lower pressures from commercial, political and control levels due to competition in industry for higher quality and higher value added, which is a controlling factor for the environment. The purpose of this article is to determine the type of cross-trade between Iran and selected trading partners and to identify its environmental impact. For this purpose, the different types of Iran’s IIT with its selected trading partners were calculated based on the Globel-Lloyd (GL), Fontan, Friedenberg and Peridy (FFP) and the Azhar and Eliot (AE) indexes over the period (2001-2015). Emprical Results show that a significant share of intra-industry trade between Iran and selected countries (including neighbours, countries from East Asia and Europe) relies on vertical intra-industry trade, indicating that there is little competitive pressure on Iranian tradable goods. According to Azhar and Eliot's index, the major share of intra-industry trade is made from low quality goods. Hence, choosing such a trade strategy has not led to improvement of Iran's environmental quality. The implication of the empirical findings figures out the policy of IIT flows expansion in order to preserve the quality of the country’s environment.

Today, the Shanghai Cooperation Organization is considered as a major regional organization in order to pursue trade liberalization among it’s members. Since Iran is now an observer state in the Shanghai Convention and is at the stage of its accession to the treaty, the purpose of this study is to assess the potential economic impacts of Iran's membership in the SCO using the Global Simulation model (GSIM). Accordingly, four scenarios including 25%, 50% and 75% reduction in tariff rates (incomplete liberalization) and 100% eliminatiom (full liberalization) in tariff rates are considered. The effects of tariff liberalization are estimated at 13 major export commodities in both scenarios. Research findings suggest that joining Iran into the Shanghai organization and eliminating tariff rates will increase the net welfare and cause trade creation in the Iran and Shanghai bloc. However, the welfare effects and the degree of trade creation in full liberalization are more than incomplete liberalization.Therefore, it is possible to consider Iran’s membership in the Shanghai agreement as a useful convergence.

Based on the list released by the international organization for standardization (ISO) on January 1st, 2014, there are almost 250 types of currencies in the world for product/service trade and financial flows. The most obvious types of currency are the US dollar, Canadian dollar, Euro, British pound , Japanese Yen, Switzerland Frank, Chinese Yuan, etc. (Evans, 2014).Exchange rate is determined by its supply and demand while the governments can affect it through different ways. The amount and nature of government involvement in the exchange rate markets define the exchange rate systems. In fact, the exchange rate systems are a framework for determination of the price. There are generally three groups of exchange rate systems including floating, fixed, and managed system. In the floating exchange rate system, the exchange rate is only determined by the market forces without the involvement of the government. The exchanges change continuously because the exchange supply and demand have volatility. In the managed exchange rate system, the exchange rate can be changed while the governments participate in the exchange markets to affect the exchange rates. In the fixed exchange rate system, the governments demand for stabilizing the exchange rates through participation in the market or regulating systems (Rittenberg, 2012).

Selecting an appropriate exchange rate system is of great importance for an economy because it affects the exchange rate and other economic variables of a country (e.g. the general level of prices and production). Determination of the exchange rate system after the collapse of Bretton Woods system became more important because there was already a kind of fixed and somewhat adjustable exchange rate system in the countries. After the collapse of Bretton Woods system, the countries such as the petroleum exporting countries questioned which exchange rate system is more important for their economies. In such countries, the petroleum export was considered as a main factor affecting the exchange rate because this factor affects both export and government revenues as well as the exchange rate system in such countries. One of the important frameworks to select the exchange rate system was the exchange rate protective property. Based on this framework, each exchange rate system protecting the economy of the country against the entered shocks is appropriate for its economy (Komijani&Arabi, 2002).

The main purpose of this study was to determine the framework exchange rate system for OPEC member countries during 1990-2015. By using the method and results of this study, the exchange rate markets and policymakers can select an appropriate system for their countries to have the minimum volatility for the exchange rate resulting in no negative effect on the economy of their country.is study, the models of Argy, Multiple-criteria and decision-making were used to select the proper exchange rate system in OPEC member countries.In the first model, after explaining the Argy model and presenting six price and production functions for all fixed, floating, and managed exchange rate systems, Chow, Hausman, Breusch and Pagan, Heteroscedasticity of variance, and autocorrelation tests were performed by STATA software. Then, based on the data collected for 1990-2015, the parameters of the above six parameters were estimated by GLS method and the production and price values were calculated by Excel software. Finally, the loss function was obtained for each country and exchange rate system by calculating and adding the numerical value of production and price variance.

The results showed that the managed rate system was selected as an appropriate system for all OPEC member countries except Ecuador, Qatar, and Nigeria because the loss function value for this type of exchange rate system was less than the other exchange rate systems. The appropriate exchange rate system for all above mentioned countries was the fixed exchange rate system. As a general result in the studied period, the proper exchange rate system for OPEC member countries was the managed exchange rate system. In the second model, the analytical hierarchy model was used. so that, the factors affecting the evaluation and selection of an appropriate exchange rate system were categorized in three groups of fixed, managed, floating, and 33 sub criteria. The results obtained from by using the weight of qualitative data in Expert Choice software showed that the managed exchange rate system with the weight of 70.1% was the most appropriate exchange rate system and floating exchange rate system with the weight of 19.6 and fixed exchange rate system with the weight of 10.6 were respectively after the managed exchange rate system. In addition, in the managed exchange rate system, the export with the weight of  29.8%, general level of prices and production with the weight of  22.5, and economic efficiency with the weight of 13.3% were the most effective sub criteria for the managed exchange rate system.

As the results of both models indicated, the proper exchange rate system for OPEC member countries was the managed exchange rate system.Based on the important role of exchange rate system in determination of exchange rate and its effectiveness on macroeconomic variables and helping the policymakers to better select the exchange rate system, considering the managed floating exchange rate system is suggested.

IF the economy is exposed to Continuous and unexpected Expansionary Monetary Policy, the exchange rate will exceed its long-run value in the short run and returns to that level again in the long-run, This is a short- run phenomenon, Stem from a lack of uniform of Adjustment speed in commodity and asset markets. Considering the destructive and harmful effects of exchange rate overshooting in the economy. In this study, the causes of the formation and effective factors on exchange rate overshooting of Iran & Organization for Economic Co-operation and Development countries using annual time series data for mentioned countries according to published statistics of World Bank, IMF and Federal Reserve by pooled model in the period 1990-2016 were investigated. Among the factors affecting exchange rate overshooting, there are variables of balance of payment, fiscal policy (government expenditures), monetary shock and oil shock which are examined in detail. In order to estimate effect of oil shock in countries surveyed, using dummy variable, the oil exporting and importing countries are divided. The results indicate a positive and significant effect of variables of fiscal policy (government expenditure), monetary shock expectations, oil shock in oil importing countries and a negative and significant effect of oil shock in oil exporting countries and balance of payments. That means, more government expenses, balance of payments deficit, monetary shock expectations and oil shock in oil importing countries will make exchange rate to overshoot or money depreciation of the country's national currency. While, oil price shock in oil exporting countries decreases exchange rate overshooting or money appreciation of the country's national currency which sign of all coefficients are fully justified according to theoretical basis of the economy.