نشریه اقتصاد و الگوسازی
پیاپی 27 (پاییز 1395)

Determining optimal path of economic variables in order to reach a specific target has great importance in optimal control method. In this study, with the use of Schumpeter's endogenous growth model, we analyse the role of invention, innovation and investment in research and development on economic growth. Also, through dynamic optimization method the path of Iranian economic growth in long run was obtained. The results of simulation with using indicates that optimal growth has positive relation with return on research and development, product quality, scale of economy and the period of planning. Also, optimal growth has negative relation with the time preference.

The aim of this study is to examine the nonlinear behavior of nominal and real variables on inflation based on seasonal data for the period 1990:3-2014:1 using TAR model. Liquidity growth recognized as threshold variable and rate of 5.57 percent (22.28 percent per year) as the threshold value. In the regime of low liquidity growth, inflationary expectations and the exchange rate fluctuations are the most important determinants of inflation in the economy. In addition, price levels in the low regime lost its long-run equilibrium relationship with other nominal and real variables. In high liquidity growth regime, inflationary expectations, liquidity growth and inflationary uncertainty are considered as the most important determinants of inflation. In addition, the price level deviation from long-run equilibrium relationship is an important factor in the inflationary acceleration, so inflation reacts to this gap rapidly. GDP and its lag in the both regimes is anti-inflationary and this impact is much stronger in low regime and oil revenues in each regime has no such an inflationary effects.

This paper employs a mixed frequency error-correction model in order to forecast monthly inflation rate for variables sampled at different frequencies. It is shown that the precision of the model is confirmable according to out of sample predictions for months Mehr and Aban of 1395. The model is then used to predict the inflation rate of the month Azar of 1395 for which no data is released yet. The predicted inflation rate, after revising three times as new information become available through time, was turned out to be 8.8 percent.

An important question related to a tax system is that how fast the tax revenues respond to economic growth. Would the percentage change in tax revenue be more or less than the GDP growth rate? This information has value to the policy makers in order to judge the appropriateness of a tax system and induce changes if necessary. The index which normally provide such an information is the tax buoyancy. This article attempts to estimate tax buoyancy using co-integration technique, and Auto-regressive Distributed Lag (ARDL) method for the period 1359-1393. The results based on the long run equilibrium relations indicate that total tax buoyancy as well as direct and indirect tax buoyancy are more than one. This finding indicate that tax revenues grow faster than the GDP growth rate. Hence the share of tax revenue in the government budget would increases over time and there is no need to adjust the tax system and the tax rates.

Energy is one of the main inputs of production process. The scarcity of this valuable input has increased the importance of attention to its efficiency and higher energy efficiency leads to higher economic growth rates. The goal of this research is to estimate energy efficiency in quadruple sectors (agriculture, industry, transportation and services) of Iran’s economy, separately with the aim of increasing precision of calculations and improving quality of results. The efficiency of energy consumption in these four sectors is estimated with the use of a translog stochastic frontier analysis (SFA) and data for 1373-1391, based on theoretical and empirical grounds. Findings indicate that not only energy efficiency of these sectors were declined during the period considered, but the average energy efficiency of all sectors had also a declining trend. The technical efficiency in all sectors were increasing, of course slowly, in contrast to the trend of energy efficiency. The services sector has the lowest energy efficiency.

The Iranian government spends billions of Rials for basic goods each year to maintain or Increase consumer's welfare level. Meanwhile the rise of inflation reduces their welfare levels. If the government attempts to compensate these negative effects a measure for assessing the severity of consumer's effectiveness is necessery. The purpose of this paper is to measure the negative welfare effects resulting from rise of inflation rate on the consumer's welfare through extracting and calculating compensating variation (CV) based on the AIDS expenditure function. The findings given the CV criterion reflects that in order to compensate the welfare effects (over the 1975-2013 period) the government should have paid on average 13 percentage of total expenditure annually to every urban household with size 4.5 person. Measuring the CV correlation coefficient with the annual inflation rate of different commodity groups indicate that the commodity groups of housing, Food and Health Care have the highest negative welfare effect with 96, 61 and 67 percent on the urban consumers respectively.