سعید دهقان خاوری

In this study we examined output gap in the Iranian economy. The main question of the study is that how much is seasonal output gap in Iranian Economy and which factor affects gap variation. The other question is that whether using HP-F as a statistical based method for estimating output gap, provide different result than using SVAR as theory based method. Accordingly the aim of study is to estimate potential output and thus output gap using two method and analysis of the result. We used two methods (Hodrick-Prescott Filter and SVAR) to estimate quarterly output gap for the period 1988:1-2008:4. The results pointed out that the estimation is not sensitive to the method and there is a close relation between oil revenue and output gap. In the period of 1998:3-1999:3, when oil price reduced to $11.45 per barrel, Iranian economy faced with a recession and it affected on output gap with a lag. Output gap increased from 34818 in 2004:1-76782 million dollars in 2008: 4. The comparison of estimated output gap and changes of oil price in different periods point out the positive relation. According to the estimations of output gap, output gap in the Iranian Economy has intense fluctuation due to the effects of oil proceeds fluctuations. In some years, actual output is more than potential output, that is, output gap is positive and so this situation can be an important reason for inflation in that period and policy maker must do plans and policies for control of inflation and in some years, actual output is less than potential output and this means output gap was negative. This situation is a reason for unemployment in these years and therefore policy makers must do expansionary policies.

This paper examines potential output with alternative methods for the period 1978-2008 using annual data of the Iranian economy. We applied Hodrick - Prescott Filter, Production Function and SVAR methods for estimation of annually potential output. The results show that the turning points for these methods look similar and almost produce similar results for output gap. Also the estimated potential output and output gap are conformed to economic and political events as output gap has decreased in war period (1980-1989) because of war expenditures, reducing production and therefore decreasing GDP. Also Iranian economy has been faced with negative output gap and therefore a severe recession because of the crisis in South East Asia in late 1990s. Gap trend is uprising after 2005 for the reason that happening oil shock and economic advancement for increasing oil income.

The ultimate goal of investments in stock markets is to earn a satisfactory return on investment, but this is difficult to achieve without enough information to predict stock returns. Information asymmetry refers to a situation where some investors have access to private information that is not reflected in the prices and is yet to be revealed to others. Information asymmetry as a market failure can lead to adverse effects such as poor investor decisions, increased corporate investment risk, and finally reduced stock returns. The issue is important in capital market of developing countries particularly due to the incomplete voluntary disclosure of information as well as its low quality and defective regulatory system. Therefore, in this study, effect of information asymmetry on stock returns has been investigated in a select group of companies listed in Tehran Stock Exchange. The analysis of this relationship was conducted dynamically for the short-term and long-term using Westerlund and Dumitrescu-Hurlin tests and Generalized Method of Moments to achieve articulated results. Using the tests is suitable with cross-sectional dependence of variables and error terms. Also, using the method is appropriate for measuring lagged effect of dependent variable and removing the bias caused by the endogeneity of explanatory variables. The Results demonstrate a significant relationship between information asymmetry and stock return dynamically in short- and long-run. The results show that there is a negative systemic effect of information asymmetry on stock return. Also, debt to asset, profit to sales, firm size and lagged stock return effects are significant.