چکیده:
One of the important topics in any industry is investigating the existence of productivity and the factors affecting productivity in that industry. The important question of this research is: what factors affect productivity in Iran's manufacturing industries? For this purpose, 21 manufacturing industries in Iran were tested for the years 1392-1393. In this article, first, the Ellison-Glaser index is introduced as one of the best indices for calculating geographic concentration, and the level of industrial concentration in the country is calculated based on this index. Then, using the Kikoni and Hall (1991) model and some previous studies, an empirical model regarding the determining factors of firm productivity was designed to empirically test the effect of concentration on productivity. The GMM method was used for estimation. Based on the estimated results, the concentration of industrial activity has a positive effect on productivity. Also, the results indicate the existence of an inverted U-shaped relationship between concentration and productivity. On the other hand, the results show that the impact of previous period productivity, labor force, and research and development on productivity is positive and significant. Additionally, the estimated coefficient of the Ellison-Glaser interaction term with labor is positive and significant, which shows that higher concentration, in addition to its direct impact on productivity, also leads to improved productivity through improving the quality of the labor force.
خلاصه ماشینی:
1 -Silicon Valley 2- Economic Geography 3- Krugman 4- Agglomeration 5- Neary 6- Duranton and Puga 7- Ciccone 8- Lall, Shalizi and Diechmann 2- Concentration and Productivity 2-3- The nature of concentration and potential effects on productivity Following the work of Krugman, numerous theoretical foundations were developed to expand the theory of concentration 3.
Based on Porter's definition (1998), industrial concentration refers to the geographical clustering of a group of firms and institutions that are linked by a specific production or economic activities.
In this model, a explicit and specific role is given to density, and the production function for producing the final good in each unit of space is considered as follows: (refer to page image) m is the amount of labor used directly in the production of the final good, i is the amount of composite input services that cannot be transported outside that range, α represents the diminishing returns relative to the two variable inputs per unit of space (congestion effect), and b is a distribution parameter (agglomeration effect).
(refer to page image) In this equation, the variables are: PRO: industrial productivity EG: Ellison-Glaser concentration index K: capital stock L: labor force R&D: research and development costs considering the power degree 2 for concentration, there is a possibility of an inverse U-shaped relationship between concentration and productivity.
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