فصلنامه تحقیقات مدلسازی اقتصادی
سال سیزدهم شماره 47 (بهار 1401)

The corona pandemic is a phenomenon that has caused a crisis in the world due to its rapid spread and unstoppable nature. This crisis, however, seems to have a purely medical and health-related nature. But it is a multidimensional phenomenon which effects and consequences can be studied and evaluated in various fields.The purpose of this study is to propose an appropriate approach in implementing the choice experiment method from the perspective of heterogeneity expressed in individuals’ preferences. In the present study, using the choice experiment method, the factors influencing the selection of individuals from the options of the selection sets (including mental illness, unemployment, change in social activities, family problems, concerns about social discriminations) have been identified. Because in choice experiment some respondents may not consider all the features or levels provided; This causes heterogeneity in the behavior of respondents. To investigate the effect of this heterogeneity on the selection process of different individuals in the sample population (Tehran), in this study, a new approach of endogenous attribute attendance in the logit model was used. The information required for the research was obtained by completing 384 questionnaires completely randomly by different people in 2021. The results of estimating the two logit models in terms of endogenous attribute attendance (EAA) and conditional logit indicate that the average tendency to Payment for features defined in the model (EAA) is higher than the conditional logit model.Because the EAA model considers the probabilities of the absence of certain features in individuals' preferences, it will have reliable results for estimating the willingness to pay.

The main objective of this article is to investigate the effect of the tax burden and corruption perceptions index, as well as the interactive effect of these two variables on the total factors of productivity, using the panel data of 18 countries in the Middle East and North Africa region (MENA) during 2002 - 2020 and Pooled Mean Group (PMG) method. The results of the study showed that increasing the tax burden without the corruption perceptions index reduces the productivity of the production factors in both the short and long term, While the increase of the corruption perceptions index  and the joint effects of the corruption perception index and the tax burden have a positive and significant effect on the productivity of all production factors. The positive interaction effect of the tax burden and the corruption perceptions index on the productivity of the total production factors indicates that the increase in the corruption perception index reduces the negative effect of the tax burden on the productivity of the total production factors. An increase of one unit of the tax burden has had a negative and significant impact of 0.027 and 0.019 units on the productivity of all production factors in the short and long term, respectively, While the increase of the corruption perception index and the interactive effects of the corruption perceptions index and the tax burden are 0.022, 0.041 a and in the long term, 0.048 and 0.069 units have had a positive and significant effect on it.

The price of crude oil is one of the factors affecting economic indicators. Therefore, the prediction of oil prices and the accuracy of the applied methods have always been discussed by economists. In this study, the effect of all effective variables on the supply and demand of crude oil based on McAvoy's competitive theory is investigated, and the supply and demand are estimated using the system of simultaneous equations and conventional statistical methods. Then, using algebraic operations and the assumption of equality of oil supply and demand in the long term, the long-term potential of oil supply and demand is extracted with respect to each of the variables in the model. Based on the results, the world's gross domestic product (GDP) has the greatest impact on oil prices with a demand potential of 0.6039, and the world's military and security tensions have the least impact with a demand potential of –0.0110. After estimating the model, the prediction accuracy of three combined mothod is compared with conventional and single-variable methods of neural network and ARIMA. These three combined methods are: (a) neural network and system of simultaneous equations, (b) ARIMA and system of simultaneous equations, (c) neural network and ARIMA and system of simultaneous equations. The results showed that the combined method of ARIMA and simultaneous equation system provides better reslts for 5-year forecasts while the combined method of neural network and ARIMA and simultaneous equation system shows better results for 10-year forecasts.

The pension coverage of the Iranian Social Security Organization for self-employed workers is offered at three contribution rates of 12, 14 and 18 percent, but looking at the statistics shows that the demand for these types of insurances is low. This research investigates the characteristics of these insured groups by using data mining and applying two machine learning algorithms, decision tree and random forest, and predicts their behavior by providing a classification model. This will help the Social Security Organization to improve customer relationship management. For this purpose, the information of 1286174 insured persons of self-employed in 2020 was used, which includes the characteristics of age, gender, average monthly income, the years of service, and the type of self-employed pension scheme. The obtained results show that women mainly apply for the scheme with 12 percent contribution, while men tend to be covered by schemes with contribution rates of 14 and 18 percent due to the burden of supporting the family. Also, for men, the demand for schemes of 14 and 18 percent increases with the increase of age, income and years of service, but there are no such trends for women. According to the obtained results, years of service and then gender are decisive in choosing the type of pension scheme in such a way that according to the prediction of the model, people with less than 4.5 years of service are known as definite applicants for 12 percent self-employed pension scheme.

In this paper, in order to determine the optimal minimum wage policy in Iran, in the framework of the new Keynesian theory, a Dynamic Stochastic General Equilibrium (DSGE) model was estimated for a small and open oil-exporting economy, according to the structure of Iran's economy in the time range of 1190 to 2019. In this model, the nominal rigidity and work habits in the supply and demand sectors are considered, and in order to simulation the economic conditions of the country, meanwhile classify the labor market in two parts; the skilled  (whose maximizes its wage based on its utility) and  unskilled labor, the model has  considered to four parts. The main purpose of this study is to answer the question of determining and adjusting the annual minimum wage based on which of the indicators of inflation, the growth of the total wage and a combination of inflation indicators and productivity of production factors, in a situation where the economy is exposed to markup of wages and prices shocks, supply and the demand of the economy and monetary and financial policies, was optimal and it causes the least negative fluctuation (deviation) on macroeconomic variables including inflation, employment, production, consumption and investment. Based on this study, three scenarios were designed and the effect of minimum wage on economic variables was analyzed. The results of the simulation and estimation of this model, which indicate the matching of the moments of the simulated data with the real world data and based on calibration in all three scenarios, it shows that the selection sum of inflation growth  and the productivity indexes to adjust the minimum wage policy, although it has cyclical effects on inflation, in comparison to other scenarios, it has the least negative deviation on economic variables and can be used as an optimal indicator for choosing the minimum wage in the Supreme Labor Council of the country.

Why are some countries rich and others poor? And do poor countries converge toward rich countries in terms of economic performance? There are questions that have occupied the minds of economists for a long time, and the answers to these questions are the basis of the formation of economic growth patterns. During the development of developing countries, it is discussed whether institutional and structural homogeneity is a prerequisite for income convergence and performance of developing countries. Our research deals with institutional analysis in developing countries. Therefore, in this research, the formation of institutional and income convergence clusters in developing countries during the period of 2002-2020 has been investigated using the log t test of Phillips and Soule (2007, 2009). The results show that the convergence of institutional indicators among developing countries is rejected. However, the results of the cluster method provide strong evidence of the existence of converging clusters among developing countries. Also, in this study, the clustering of the per capita income of the studied countries has been done, which shows similar results to institutional clustering. which indicates that institutional clusters may be effective in forming income clusters.