Journal of Economic Modeling Research

---

  Public-Private Partnerships (PPP) models using the capacities of private sector have provided a background to supply public services and infrastructures in different ways. Transportation sector as a fundamental sector of economic development in Iran needs public-private participation models. For this purpose a theoretical literature of public-private partnerships has been reviewed and then the barriers to the development of such partnerships in transportation sector of Iran economic, infrastructure, legal and social areas were investigated. Finally with AHP, TOPSIS and SAW methods of Multi Criteria Decision Making (MCDM)the barriers were prioritized and their relative importance was analyzed. The results of three methods indicate that factor of financial markets limitations and availability of financing is the main barrier to the development of public-private partnerships. Although there is a little different among the results of TOPSIS in rating some final factors compared to other two methods, by calculating rank correlation coefficient (Spearman) the null hypothesis(the lack of correlation between the results) was rejected and with 99.75 percent probability all of the result are similar. Ranking results of barriers to the development of public-private partner ships in this study can be taken into consideration in policymaking and determining the requirement to use these models in the fields of transportation and other infrastructural areas.

---

  In recent years, financial economists have increasingly recognized the interaction between market structure and capital structure or financial decisions of the firms.

  This research analyzes the relationship between market structure (power) and the capital structure (leverage ratio) of listed companies in Tehran Stock Exchange (TSE) based on static and dynamic approach. In this research we study a balanced panel dataset of 101 firm-year observations from 2006 to2010 and test significant relationship for testing hypothesis.

  First we use pooled regression to determinant the relationship between capital structure, market structure (Tobin's Q) and five control variables including profitability, size, collateral value of assets, growth rate of assets and uniqueness of assets. After employing chow and hausman test, we selected fixed effect panel data model. Also we employed GMM method to have more efficient result and also to cope with the unobservable firm-specific characteristics and endogeneity problems.

  Our results suggest that the relationship between leverage and market structure is non-linear (cubic) due to the complex interaction of market conditions, agency problems and bankruptcy costs. The study finds a negative relationship between capital structure and profitability and also positive relation between capital structure and the size. So, profitable companies tend to use internal financing such as retained earnings and issuing new shares instead of debt financing. Also big companies prefer to use more leverage due to desirable conditions for getting loans. Our evidence shows that Iranian listed companies are generally more subject to agency cost theory (limited liability effect) and tax shield theory. Finally, the system-GMM results reveal that managers of Iranian firms tend to adjust dynamically their leverage ratios over time.

 

---

This paper presents an AHP and FLP model for the allocation of energy subsidies to different economic sectors. To do so, we defined a group of socio-economic criteria that may affected by the allocation of energy subsidies. These criteria are: economic growth, energy intensity, labor intensity, inflation, social cost of air pollutions and distribution of energy subsidy among socio-economic levels. According to calculated weights, we determined the priority of the above mentioned criteria. Also, according to the optimum overall rank of economic sectors, the commercial sector has the highest rank followed by industrial, agricultural and household and transportation sectors. After determining the final coefficients of AHP approach, we determined the allocation of energy subsidies using linier programming approach. We also considerd the change in technology and consumption patterns of household and transportation sectors. Results show that the share of energy subsidies allocated to commercial and transportation sectors should increase to 30.4 and 28.6 percent respectively.

---

Fiscal decentralization that is considered a transfer of responsibilities that associated with accountability to sub – national governments, increases efficiency and providing better access to public goods in the Economy. According to the five-year development plans of Iran creating and allocating structure for provincial budgeting, fiscal decentralization generally is moving in the costs of its Provinces in order to give more responsibility to the provincial development projects. The aim of this study is an investigation of effect for partial fiscal decentralization on regional economic growth of Iran. Fiscal decentralization index is proportion of provincial's capital assets to government's capital assets, So this researches the effects of decentralization on economic growth in the framework of Solow's growth model. That the results based on data from 30 provinces between 2000 and 2007 on the panel data estimation, shows partial fiscal decentralization which has a non-linear relationship with the growth (convex shape) and partial fiscal decentralization Indicts the Optimal degree in growth of regional economy in Iran.