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The investigation of determinants in Gross National Saving behavior especially effect of corruption, is one of the important issues in macroeconomics literature. For this purpose, we use the corruption perception index in dynamic panel data approach (Arellano and Bond Method). The Empirical results indicate that the corruption perception index (reduction of corruption) has positive and significant effect on the gross national saving. The main results of model estimation for two groups of oil and non-oil countries of MENA, shows that in oil countries the elasticity of gross national saving is more than of non-oil countries and reduction of corruption can be increase the national saving in oil countries. Moreover the results of model estimation shows that the inflation rate has negative effect and real per capita income and terms of trade variables have positive and significant effects on the gross national of saving in these countries.

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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.

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Price shocks lead to oil price volatility in world oil markets. In response to this volatility, economic growth may take different regime and behavior patterns in different situation. Investigating this multi behavior patterns can be useful for policymakers to reduce the effect of oil price volatility. In this study, an EGARCH model has developed using the seasonal data of OPEC oil basket nominal prices during 1367:Q1-1389:Q4. Markov switching models is also applied to investigate the multi behavior patterns of economic growth in response to oil price volatility in Iran. The results show that positive oil price shocks sharply lead to formation of oil price volatility, but, the negative price shocks will slightly reduce oil price volatility. Iranian economic growth is affected by this volatility under three different behavior regimes. If the economy switch to one of the regimes (low, medium, high economic growth), the probability of transition between these regimes and their duration is different. So, oil price volatility as a reason for low economic growth in Iran may cause the economy switch to its lower situation.