نشریه پژوهش های اقتصاد صنعتی
پیاپی 14 (زمستان 1399)

Analysis of financial markets time series is an aspect of finance which is important to both investors as well as regulators. In particular, the validity of the efficient market hypothesis plays a significant part in such considerations. In this regard, the (weak) efficient market hypothesis is usually investigated within the random walk theory with tools such as rescaled rang analysis. However, it is by now well-known that markets are complex system, whose technical analysis requires tools for complex systems theory. We therefore use the Multi-Fractal Detrended Fluctuation Analysis (MFDFA) in order to addresses the degree of market efficiency in various sector of industries in the Tehran Stock Exchange. We choose the largest sectors and analyze their daily price indices for the period of March 2008 to December 2020. For each of the sectors we calculate the generalized Hurst exponent as well as singularity exponent and singularity spectrum. We next use various measures of market inefficiency based on Multi-Fractal analysis (width of singularity spectrum) in order to rank these sectors in term of their inefficiency index. We find that while oil products and metallic mineral products sectors rank high on inefficiency, diversified industrials and base metals, rank relatively lower. We also note that a measure of standard Hurst exponent indicates that all considered sectors are relatively inefficient when compared to other Islamic Stock Exchange indices.

Entering the global market for medical equipment requires that the export product be of appropriate quality and comply with international standards to be able to compete in the global market. The main purpose of this article is to evaluate the impact of entrepreneurial capabilities on the export of medical equipment from developed and developing countries. For this purpose, while using the data of the period 2014-2019, a panel data Model was used to evaluate the impact of various factors, including entrepreneurial abilities on the export of medical equipment. In this research, elements such as  opportunistic start-ups; Technology absorption; Human capital and competition were considered as indicators of entrepreneurial ability. The results showed that the above indicators have a positive effect on the export of medical equipment in both groups of selected developing and developed countries.Accordingly, exporting equipment products requires increasing the entrepreneurial capabilities of companies through various incentives.

The purpose of this article is to evaluate the intensity of learning in the Iranian banking industry during the period 2001 to 2016. During the period under review, the Iranian banking industry consisted of 10 state-owned banks and 17 private banks. In order to evaluate the realization of learning in the Iranian banking industry, a Cobb-Douglas cost function was used. In this function, loans and facilities were considered as inputs as well as labor, capital and bank deposits as inputs. After adjusting the cost function, this function was converted into a learning curve and then the learning curve was estimated. In the learning curve, the cumulative amount of loans and facilities was used as an indicator of experience. The results indicate that the slope of the learning curve is in line with negative expectations, which is as if learning has been achieved in the Iranian banking industry in the period under study, but its intensity is low. In addition, the results indicate a constant return to scale in the Iranian banking industry.

Presence in world trade is one of the concerns of any country because it provides the opportunity for economic growth and development. Export of refineries products can have a positive ef     fect on the process of Iranian economic growth and development. Therefore, it is necessary to evaluate the comparative advantage in the production of refinery products. The purpose of this article is to measure the price competitiveness of Tabriz Refinery in International trade of refinery products. For this purpose, the Internal Resource Cost Index (DRC) was used along with the elasticity of this index to global price changes. According to the data of  1396 AH, it was determined that this company, while having a comparative advantage in gas oil, fuel oil, Kerosene, LPG, bitumen, slops wax, ethane, naphtha, vacuum bottom, lobcat, solvent  402 and jet fuel but has no comparative advantage in production and export of butane and sulfur. considering the real exchange rate, results also showed that the DRC index is price elastic  for  products such as gas oil  and fuel oil, but is inelastic to gasoline Price decrease.Based on the obtained results, it is suggested that due to the lack of sulfur and butane advantages, these products should be removed from the production process and for more profitability,  moving towards the development of a new generation of refineries (Petro Refineries) is required.

The main purpose of this paper is to investigate the nonlinear relationship betweentypes of intra-industry trade and inflation rate using the panel smooth transition regression model for selected developing countries during the period 2001-2016. In the framework of new trade theories, the relationship between intra-industry trade and inflation rate is not definite and clear, and the relationship depends on market structure, product differentiation and economies of scale and other factors such as tradeliberalization, exchange rate pass through, government size and human capital. For examining the relationship between types of intra-industry trade and inflation rate, two empirical models each in four cases have been used. In general, the results show that increases in vertical and horizontal intra industry trades reduce inflation rate which confirms the results of Krugman studies (1981, 1979). An increase in inflation also reduces vertical and horizontal intra-industry trades. According to the obtained results, it seems that enhancing intra-industry trade, especially horizontal one could improve foreign trade as well as control inflation.

The purpose of this study was to investigate the relationship between diversity and bankruptcy risk. The statistical population of this study includes all companies listed in Tehran Stock Exchange during 2018-2007. The sample is based on the systematic elimination method of 82 companies. The product diversification strategies are divided into related, unrelated, total, and competitive diversification. Also, the bankruptcy risk is based on the Z index. The method of research is based on multivariable regression with panel data model using ordinary least squares method. Research evidence suggests that by adopting product diversification strategies, companies' reaction to the bankruptcy risk is negative. In other words, companies can use diversification strategies as a mechanism to get rid of bankruptcy when they are in critical situations. With 1% increase in diversity strategies, the risk of bankruptcy in the direction of adoption of the diversification strategy was 2.20%, the non-relevant diversification strategy was 9.9%, the diversification strategy was 4.2% and the adoption of the competitive diversification strategy was 0/15% decreases.