فصلنامه تحقیقات مدلسازی اقتصادی
سال سوم شماره 12 (تابستان 1392)

The commitment and forward-looking behavior of central bank is of great importance. Commitment imposes less social costs on the central bank and the public. However، while there is wide agreement on the importance of commitment، there is much less consensus on how to implement commitment through targeting or instrumental rules. In this paper، we have estimated a basic New Keynesian model in Iran economy based on quarterly data over a sample period for 1990-2010. Then، we introduced a kind of instrumental rules that is called Speed Limit rule. The main feature of this rule is that the output gap is replaced by the changes in the output gap in the central bank''s loss function. Then، by calculating appropriate weights under alternative targeting rules، we showed that this rule has the lowest social costs. Then، assuming the use of interest rate as primary monetary policy by the central bank، it is optimal to consider the role of the changes in the output gap (i. e. speed limit rule) in addition to the role of inflation and the output gap. As we expected، the estimation results of this instrumental rule in Iran economy showed that this rule has not been used for determining the interest rate. In other words، among the variables considered، only inflation rate has a positive and significant relationship with the interest rate، and the output gap and the changes in the output gap are not used in determining the interest rate.

Dominance of arid and semiarid climate in a vast area of Iran along with the water consumption growth necessitates a more sophisticated planning، a more efficient operation towards an optimal allocation and conservation of water resources in the country. In recent decades many countries، including Iran، have adopted increasing block tariffs for domestic water management. This policy is based on a progressive tariffs applied to control and manage the residential water consumption. In this paper، we developed a panel data model to investigate the impact of increasing block pricing on the residential water consumption during 2004-2008. The average and marginal price models of demand for residential water have been estimated to examine the effects of households’ income and the climate conditions on the residential water consumption. Results show that the increasing block pricing system has not efficiently controlled the residential water consumption in Iran.

In the current structure of world economy، imports play an important role in the economic development strategy. Although taking the suitable policies for the imports of goods and services is important، but taking the correct strategy is subject to factors affecting imports. In the most of empirical studies، imports are a function of real income and real exchange rate. So، the effect of income inequality on imports of goods and services has less been investigated. Whereas، increase in income inequality causes an increase in the purchasing power of high income people and demand for imported luxury goods and also causes a change in the composition of domestic and imported consuming goods. This study examine the effect of income inequality on import of goods and services in 17 developed countries and 18 developing countries in the period 1990-2010 using generalized method of moment (GMM) analysis. The results indicate that there is a positive relationship between income inequality and imports of goods and services in developed countries; while this relation is negative in developing countries. Furthermore، the relationship between GDP and imports of goods and services is positive in both groups of countries، while the relationship between real exchange rate and imports of goods and services is negative in both groups. Thus، policy makers should redistribute income and wealth in favor of the low income people and motivate them to participate in the production sectors، reduce the inequality gap and improve their competitiveness power in the market and enhance the income from the abroad.

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.

In this study، we designed and simulated a system dynamic model to analyze the impacts of energy intensity changes on environmental and economic indicators in Iran. Results show that if the current situation is continued، the industrial sector energy intensity will increase from 2. 67 in the base year to 2. 704 at the end of planning horizon. So، the sector will consume 540 million oil barrels to create a value added equals 490627 billion Rials in 2025. Accordingly، the amount of environmental pollutants will increase from 59 million tons in the first year to 267 million tons in 2025 and social costs of producing this pollution would be equal to 67، 449 billion Rials. These findings indicate that regarding the limitation of the production and the increasing costs of energy supply in the future، the country''s industrial policies should concentrate on technological changes to increase the efficiency of energy consumption. Also، results indicate that industrial energy consumption has destructive effects on the environment and society in the future and the costs in this sector will not be reversible.

Providing، maintaining and improving health of infants as a vulnerable group has a special place in health care. Due to the importance of this index in the United Nations development indices، we compared the socioeconomic determinants of infant mortality rate in Iran and MENA countries during 1980- 2010. The aims of this comparison was to determine major causes of inequalities in infant mortality rate in the region and also to determine why this index is very high and very low in different countries..

The structure-conduct-performance (SCP) paradigm has constituted an enduring empirical tradition in empirical industrial economics and has the advantage of clarifying the basic building blocks of the competitive mechanisms. This paper presents a SCP model to estimate causes and effects in Iranian manufacturing industry in 2009. The model used in this paper is a system of four simultaneous equations: agglomeration as the standard measure of structure، advertising and R&D as the standard measure of conduct and profitability as the standard measure of performance. Using the data from a sample of Iranian industries، three-stage least squares results indicate that: a) Advertisement has positive and significant impacts on agglomeration and profitability. b) Profitability has positive and significant impacts on agglomeration and advertisement. c) Agglomeration has positive and significant impact on profitability and also a negative impact on advertisement.