چکیده:
Concentration is regarded as one of the most important aspects of market structure and it helps us to consider market structure. It is usually used in empirical studies of market and industry structure to determine the degree of competition and monopoly. Also, it is possible to design appropriate program toward desired performance by studying time trend of concentration and recognition of effective factors on concentration variation. This study aims to investigate the effects of trade liberalization on industrial concentration in various levels of manufacturing industries (ISIC 4digits). for this purpose "Raw data comprehensive project of the industrial firms of Iran during 1994-2004" were used, Also, panel model with cross fixed effect was chosen for estimation, after doing stability test of Levin-Lin-Chu and specification tests of Chow, Brousch-Pagan and Hausman. The results show that trade liberalization has negative effect on industrial concentration and make the market structure more competitive. To investigate the effects of trade liberalization on industries with competitive and monopoly structure, two groups including low and high concentrated industries were considered. Results of this grouping show that the liberalization leads to a decrease in the level of concentration in the low concentrated group. Also, adjusted concentration index was used in order to investigate domestic market
خلاصه ماشینی:
"3. Iran Industrial Structure and its resulting Problems From including effective factors on monopoly can be pointed out to constitutional law, regulation and certain benefits and vertical merges due to high costs of legal contracts actions, government ruling, market limitations which requirement of removing limitations is economics liberalization on various dimensions.
100 , t = 1994/05, …, 2004/05 OPEN: economic openness index IMP: import penetration OUT: output SIZE: medium size of firm, on four-digit codes In order to description of trade liberalization, has been used market openness index in industry sector (MOI) to external world.
With notice to results of investigating stability test of Levin, Lin and Chu (2002), with constant and time trend, for all variables of model, the assumption based on existing unit root on variable is rejected and shows that all of these variables are high significant stability I(0), therefore it can be estimated equation of trade liberalization effect on industrial concentration.
Results arising from estimating equation of trade liberalization on industrial concentration are as follows: Table 1: Equation estimating of HHI, panel model with cross-sectional fixed effect (EGLS method) t-Statistic Coefficient Variable a 21.
While trade liberalization, because existence of many firms with small size and inefficient so, increasing of market range and easier accessibility to technology and production factors, some of these inefficient firms that include industries with relatively competitive structure, has been increased their production capacity and has led to more efficiently and Therefore, concentration rate decreases."