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     The main goal in this research is to survey and determine the actual structure of the demand function through the BOX-COX consumer goods demand system which includes various forms of demand functions. Using nested and non-nested methods the estimation of consumer demand function is done. Nonlinear seemingly unrelated regressions are also used for the periods of 1982- 2007 via the combined statistics of income groups in urban areas in order to calculate  uncompensated price elasticity and expenditure elasticity associated with the demand function estimate. Results of nested and non-nested tests show that the BCDS and AIDS models are near performance. The elasticity figures resulted from the BCDS and AIDS models have also revealed that food group is an essential one, social affairs (clothing, health, leisure and education) are regarded as almost luxury, and miscellaneous group (transportation and others) is quite luxury. But the group of housing (housing and furniture), in the BCDS model is almost luxury and in the AIDS model considered as essential. The elasticity of demand was confirmed by the demand law and cross elasticity of demand has also shown that the food group compared with the social affairs is considered as supplementary and to the group of housing and miscellaneous is regarded as a substitute. The social affairs group compared with the miscellaneous group is supplementary and to the housing group is a substitute and finally the miscellaneous group is considered as a substitute to the housing group.  

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Tax reform as a part of financial system’s reforms constitutes the core of fiscal policies and economic adjustment process. The widening tax base and rationalizing tax rates are main priorities in this regard. This paper aims to calculate optimal commodity tax rates and marginal cost of social welfare resulting from indirect taxes in Iran. The calculation of marginal cost of social welfare requires determining the own and cross price elasticities of demand and optimal tax rates for goods and services. These parameters are obtained by estimating demand function of ten good and service groups in a linear expenditure system. This system is estimated through seemingly unrelated regression method using data of ten expenditure deciles of urban households in Iran during 1996-2010. The optimal tax rates are calculated using Ramsey method in a multi-person world and Bergson-Samuelson's social welfare function. In this model, a social welfare function is maximized with respect to given tax revenue of government using Lagrange method. Results show that when social inequality aversion parameter is zero, optimal tax rates almost are equal. By increasing this parameter, which fairness rather than efficiency is considered, these rates are diverged, in a way that some commodity groups are entitled to get subsidy. In addition, as social inequality evasion parameter increases, the marginal cost of social welfare resulting from change in commodity tax rates decreases, and welfare loss gets very small in the highest social inequality evasion rate. So, decreasing subsidy among all good and service groups receiving subsidy, and increasing tax on other groups lead to decrease in social welfare.  

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Inefficiency and injustice of subsidy system in Iran over the years induced the government to implement targeted subsidy law since 2010. As a result, the share of poor households receiving government subsidies decreased. Utilizing the micro-data of Households’ Income and Expenditure Surveys (HIES) from 2005 to 2014 and applying seemingly unrelated regression(SUR) technique through feasible generalized least squares (FGLS) method, this study examines the effect of targeting subsidies on households’ consumption combination. The results show that the shares of necessary goods in households’ expenditure have increased. According to Engle theory, these indicate reductions in households’ welfare. In addition, the “subsidy” dummy variable has the most effect on food expenditure share among different goods groups. One reason for the welfare reduction is higher increase in relative prices compared to increase in income due to subsidy. Since, the permanent income is of the highest effect on allocation of households’ budget among different goods groups; therefore, policy makers should focus on increase in the households’ real permanent income instead of inflationary policies, which increase nominal cash subsidies.

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Natural resources generate the major part of national wealth in resource-rich developing countries. Based on economic theories, if natural resource rents are reinvested continuously in other forms of capital, such countries can benefit from these resources. Thus, examining the mechanism of how to rents affect economic growth through capital accumulation channels is of great importance. Because of the importance of management of resource rents in achieving sustainable growth and development in resource-rich countries, this paper investigates the impacts of resource rents on accumulation of four kinds of capital (foreign, physical, human and social capital) in Iran during 1970-2014. To this end, a simultaneous equations system consisting of various capital forms is designed, and estimated by using Seemingly Unrelated Regression estimator. According to the findings, resource rents have positive effects on accumulation of foreign, human and social capital in Iran. But it is of negative effect on accumulation of physical capital. The results show that physical capital is affected by natural resource rents more than other kinds of capital. This is because of unproductive government investments in physical capital, hence not only resource rents increase physical capital but also they affect physical capital negatively.

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In recent years, the high cost of raising livestock and, consequently, the sharp increase in the price of red meat in Iran have reduced its demand, and people consume chicken meat as a substitute for it. This has reduced the production incentives and, with the bankruptcy of some beef cattle farms, the welfare of producers and consumers of this product face serious danger. To overcome this problem, understanding cost structure and reducing consumer price by reducing production costs seems necessary. Therefore, the aim of this research was to evaluate cost structure and economies of scale of beef cattle farms in Mashhad. For this purpose, the short-run Translog cost function along with input cost share equations were estimated using the iterated seemingly unrelated regression method. The data were collected in 2017 from beef cattle producers by interview using structured questionnaires. The result showed that there were increasing returns to scale for all farms. In addition, the demands for all inputs were perfectly inelastic. On the other hand, there was weak complementary and substitute relationship between inputs. According to the results of this research, the most important factor of beef production in the selected farms was feed, whose demand was inelastic and the possibility of substituting it with other inputs was very weak. Therefore, the adoption of policies by the government, including subsidies for feeding cattle and increasing the import of this input, can reduce the production cost and prevent beef prices from rising.
 

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Water is the most important input used in agriculture. Due to the scarce water resources and dry and semi-arid climatic conditions of Iran, water demand management has special importance in the whole economy, including the agricultural sector, because this sector has the largest share in water consumption. The purpose of this study was to estimate the water demand function and to analyze the cross and symmetrical relationships between water and other inputs. For this purpose, the Ordinary, Allen, and Morishima's substitution elasticity were calculated, and the substitution and complementary relationship between water and other inputs were determined. These elasticities determine the amount and sign of cross relationship of water. In order to achieve the objectives of research, the translog cost function, along with the input share equations were estimated using iterative seemingly unrelated regressions. The information was related to crops and period (2007-2015) in Qazvin. The results showed that water was a low-elasticity input and its value was -0.75. Also, the cross elasticity with pesticide, labor, machinery and land was calculated as 0.71, 0.99, 0.93, and 0.89, respectively, which implied the substitution relationship. Investigating symmetry of elasticities also implies the asymmetry of Ordinary and Morishima elasticities and symmetry of Allen's elasticity with other inputs. In this regard, the cross elasticity of inputs of pesticide, labor, machinery, land and water were calculated as 0.28, 0.86, 0.91, and 0.90, respectively, indicating the asymmetry of this elasticity. Differences between levels of cross elasticities depend on the cost share of the two inputs and the sign of estimated coefficient.
 

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Agriculture is one of the responsible sectors for adequate food production and contribution to food security. However, due to the rapid population growth and increasing demand for food, this responsibility is becoming more and more challenging. The consequence of this challenge is the excessive exploitation of natural resources and destruction of the environment. This study aimed to investigate the cost structure, economies of scale, and inputs elasticities for the major farm crops of the Qorveh-Dehgolan Plain, in Kurdistan Province, through a translog cost function. The needed data were collected through a multi-stage cluster sampling survey in the 2017-2018 cropping year. The results showed that the average share of water input in the total production cost of the studied products was 12%. Results also showed that all ordinary own-price elasticities of demand for inputs were negative and smaller than one. However, the results of Allen-Uzawa's own price elasticities showed that demands for inputs could be elastic. Ordinary and Allen-Uzawa own price elasticity of water input were -0.76 and -6.7, respectively. The results also showed that wheat, tomato, barley, and alfalfa farms in the area under study were facing economies of scale, on average, while potato, cucumbers, and sugar-beet farms were facing diseconomies of scale.