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  This research aims to analyze the effects of industrial agglomeration on regional economic growth in the Iranian provinces. For this aim, this study is divided into theoretical and applied sectors.

  In the theoretical point of view, the research has proposed a simple theoretical framework to study the impacts of industrial agglomeration on regional economic growth. In applied sector, we have specified econometrics models and estimated them by using a system of simultaneous equations using Panel Data for 28 provinces of Iran over the period 2000-2006.

  Results show that regional economic growth is positively affected by industrial agglomeration and regional knowledge level and negatively affected by human capital mobility cost and per capita income. Results also show that regional economic growth, transportation cost, household expenditure and human capital mobility cost have positive effects on industrial agglomeration in the Iranian provinces.

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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.

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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.