Browsing by Author "Omay, Tolga"

Now showing 1 - 20 of 22

An Examination Of The Effects Of The February, 2001 Crisis (Turkey) On The Performances Of The Low-Q And High-Q Firms
(2006) Karadağlı, Ece C.; Omay, Tolga
This paper examines the effects of the February 2001 Economic Crisis (Turkey) on the low-Q and high-Q firms. In the study, our sample is composed of the firms that are actively being traded on Istanbul Stock Exchange (ISE) during that time, and is divided into two sub-samples based on their Tobins' Q values. As firms with high Tobins' Q values are supposed to have lower debt levels we proposed them to be less affected by the crises: their debt repayment commitments are lower, although they are expected to be under the burden of higher interest rates. On the other hand, low-Q firms have incentives to overinvest due to the high levels of available free cash and they may be under the burden of some perquisites expenses. But because of the asset substitution affect, the investments undertaken by low-Q firms are expected to be safer projects while high-Q firms may have undertaken more risky projects. To test our hypothesis that the crisis would affect the low-and high-Q firms to differing extends, we construct the average mean excess returns of both sub-samples and use the Large Sample Test of Hypothesis About a Population Mean method. Our results mainly confirm our expectations: we found that the average mean excess negative returns of high-Q firms were higher than that of low-Q firms during the February 2001 Crisis, indicating that high-Q firms are more riskier in an economic crisis setting than low-Q firms, which in turn implies that the effects of the conflict between equityholders and debtholders dominate the affects of the conflict between managers and the shareholders.
Are the Transition Stock Markets Efficient? Evidence From Non-Linear Unit Root Tests
(2007) Omay, Tolga; Hasanov, Mübariz
In this paper we address efficiency of eight transition stock markets, namely, Bulgarian, Chinese, Czech, Hungarian, Polish, Romanian, Russian and Slovakian stock markets by testing whether the price series of these markets contain unit root. For this purpose we employ the nonlinear unit root test procedure recently developed by Kapetanios et al. (2003) that has a better power than standard unit root tests when series under consideration are characterised by a slower speed of mean reversion. The results of nonlinear unit root tests indicate that only Bulgarian, Czech, Hungarian and Slovakian price series contain unit root, consistent with weak form efficiency.
Can Term Structure of Interest Rate Predict Inflation and Real Economic Activity: Nonlinear Evidence From Turkey
(Springer, 2011) Omay, Tolga
Citation - WoS: 12
Citation - Scopus: 12
The Effects of Inflation Uncertainty on Interest Rates: a Nonlinear Approach
(Routledge Journals, Taylor & Francis Ltd, 2010) Hasanov, Muebariz; Omay, Tolga
In this article, we investigate the effects of inflation variability on short-term interest rates within a nonlinear smooth transition regression framework. The test results suggest that only the conditional mean of the inflation is a nonlinear process whereas the conditional variance is time variant but linear. Using the square root of conditional variance as a proxy for inflation risk, we estimate Fisher equation augmented with inflation risk. Although the estimated Fisher equations suggest that inflation risk reduces short-term interest rates, we find that the effects of inflation risk on interest rates are regime-dependent. Particularly, we find that the negative effects of inflation variability on nominal rates are greater in low-inflationary regimes when compared to high-inflationary regimes. On the other hand, it is found that both inflation and inflation uncertainty raise the expected inflation effect.
Fractional Frequency Flexible Fourier Form to approximate smooth breaks in unit root testing
(2015) Omay, Tolga
In this study, a Fractional Frequency Flexible Fourier Form DF-type unit root test is proposed. The small sample properties of the proposed test are found to be better than that of the integer frequency counterpart. •Fractional Frequency Flexible Fourier Form-DF-type of unit root test is proposed.•The small sample properties of FFFFF-DF-type test are better than EL test.•FFFFF-DF-type test improves the empirical testing performance.•FFFFF-DF-type test prevents type two errors and over-filtration problems.
Citation - WoS: 30
Citation - Scopus: 34
Fractional Unit-Root Tests Allowing for a Fractional Frequency Flexible Fourier Form Trend: Predictability of Covid-19
(Springer, 2021) Omay, Tolga; Baleanu, Dumitru
In this study we propose a fractional frequency flexible Fourier form fractionally integrated ADF unit-root test, which combines the fractional integration and nonlinear trend as a form of the Fourier function. We provide the asymptotics of the newly proposed test and investigate its small-sample properties. Moreover, we show the best estimators for both fractional frequency and fractional difference operator for our newly proposed test. Finally, an empirical study demonstrates that not considering the structural break and fractional integration simultaneously in the testing process may lead to misleading results about the stochastic behavior of the Covid-19 pandemic.
Citation - Scopus: 4
Inflation and Growth: an Empirical Study for the Comparison of the Level and the Variability Effects
(Nova Science Publishers, Inc., 2006) Arin, K.P.; Omay, Tolga; Omay, T.; Çankaya Meslek Yüksekokulu
This paper analyzes the interaction between the inflation and growth within the Mankiw-Romer-Weil (1992) framework. Our results indicate that the inflation level has a significant negative effect on output in advanced capitalist economies, whereas inflation variability has a negative and significant effect on output in the long-run for all sub-samples. Our results also show that the variability effects are larger in terms of significance. © 2006 Nova Science Publishers, Inc. All rights reserved.
Citation - WoS: 10
Citation - Scopus: 11
Is There Convergence in Renewable Energy Deployment? Evidence From a New Panel Unit Root Test With Smooth and Sharp Structural Breaks
(Pergamon-elsevier Science Ltd, 2023) Omay, Tolga; Corakci, Aysegul
This study examines whether the contribution of renewable energy to the total primary energy supply converges in a panel of 24 OECD countries over the period 1960-2020. To this end, a new panel unit root test that allows for both sharp and smooth breaks is proposed to test for the stochastic convergence hypothesis. Although renewable energy convergence is not rejected when the newly proposed test is applied to the full panel of OECD countries, it found only moderate support within the members of the panel using a sequential panel selection methodology. In fact, in two high-income OECD countries, the contribution of renewable energy to the primary energy supply shows no sign of convergence: Poland and Iceland. Therefore, the renewable energy shares seem to be converging to a common steady state in only a group of OECD countries over the long run. This uneven pattern of convergence, in turn, suggests that the OECD countries are still far away from developing a common sustainable renewable energy target, calling for urgent international policy cooperation to encourage the divergent econo-mies to seek out the menu of policies that ensure the worldwide success of renewable energy transformation.
Is there convergence in renewable energy deployment? Evidence from a new panel unit root test with smooth and sharp structural breaks
(2023) Çorakçı, Ayşegül; Omay, Tolga
This study examines whether the contribution of renewable energy to the total primary energy supply converges in a panel of 24 OECD countries over the period 1960–2020. To this end, a new panel unit root test that allows for both sharp and smooth breaks is proposed to test for the stochastic convergence hypothesis. Although renewable energy convergence is not rejected when the newly proposed test is applied to the full panel of OECD countries, it found only moderate support within the members of the panel using a sequential panel selection methodology. In fact, in two high-income OECD countries, the contribution of renewable energy to the primary energy supply shows no sign of convergence: Poland and Iceland. Therefore, the renewable energy shares seem to be converging to a common steady state in only a group of OECD countries over the long run. This uneven pattern of convergence, in turn, suggests that the OECD countries are still far away from developing a common sustainable renewable energy target, calling for urgent international policy cooperation to encourage the divergent economies to seek out the menu of policies that ensure the worldwide success of renewable energy transformation.
Citation - WoS: 18
Citation - Scopus: 21
Monetary Policy Rules in Practice: Re-Examining the Case of Turkey
(Elsevier, 2008) Omay, Tolga; Hasanov, Muebariz
This paper investigates possible asymmetries in the monetary policy reaction function of the Central Bank of Republic of Turkey over the business cycles. It is found that the bank reacted more aggressively towards output stabilisation during recessions than expansions. The empirical evidence suggests that the inflation targeting policy of the Turkish Central Bank was accommodative rather than stabilising. Furthermore, it is found that although the Central Bank of Republic of Turkey responded to foreign reserves, real exchange rates and short-term capital inflows both in expansion and recession periods, the bank targeted money growth, budget deficits, and net foreign assets only in expansion periods. (c) 2008 Elsevier B.V. All rights reserved.
Citation - WoS: 11
Citation - Scopus: 9
Ppp Hypothesis and Temporary Structural Breaks
(Economics Bulletin, 2017) Corakci, Aysegul; Omay, Tolga; Emirmahmutoglu, Furkan; Çorakcı, Ayşegül; Tolga, Omay; Çankaya Meslek Yüksekokulu; İktisat
In this study our aim is to explore a better testing strategy for the PPP hypothesis under a temporary structural break. For this purpose we use the exponential smooth transition (EST) function in the unit root testing framework and compare this methodology with the one that uses a Fourier function. Although the Fourier function is extensively used in the literature to test the validity of the PPP hypothesis under temporary breaks, this investigation shows that it leads to misleading results.
Citation - WoS: 23
Citation - Scopus: 21
Re-Examining the Real Interest Rate Parity Hypothesis (Riph) Using Panel Unit Root Tests With Asymmetry and Cross-Section Dependence
(Springer, 2017) Emirmahmutoglu, Furkan; Omay, Tolga; Corakei, Aysegul
This paper investigates the validity of the real interest rate parity hypothesis (RIPH) using a panel unit root approach. For this purpose, first we estimate the possible nonlinear data-generating processes of the real interest rate differential series and using these estimates determine which panel unit root test is better for analyzing the RIPH. To this end, smooth transition autoregressive and threshold autoregressive (TAR) models are estimated for two different panels of countries: G7 and post-Soviet transition economies. The results show that the data displays both strong asymmetry and high transition speed. Therefore, secondly, we propose a new panel unit root test where the alternative is stationary with asymmetric TAR adjustment, and provide their empirical power properties. Finally, we demonstrate that our newly proposed test is able to provide conclusive evidence in favor of the RIPH in contrast to the other panel unit root tests considered.
Citation - WoS: 68
Citation - Scopus: 86
Re-Examining the Threshold Effects in the Inflation-Growth Nexus With Cross-Sectionally Dependent Non-Linear Panel: Evidence From Six Industrialized Economies
(Elsevier Science Bv, 2010) Omay, Tolga; Kan, Elif Oeznur
This paper analyzes the empirical relationship between inflation and output growth using a novel panel data estimation technique, Panel Smooth Transition Regression (PSTR) model, which takes account of the non-linearities in the data. By using a panel data set for 6 industrialized countries that enable us to control for unobserved heterogeneity at both country and time levels, we find that there exists a statistically significant negative relationship between inflation and growth for the inflation rates above the critical threshold level of 2.52%, which is endogenously determined. Furthermore, we also control cross-section dependency by using the CD test modified to non-linear context and remedy cross-section dependency with Seemingly Unrelated Regression Equations through Generalized Least Squares (SURE-GLS) and newly proposed Common Correlated Effects (CCE) estimation techniques. We find that these methods change the critical threshold value slightly. The estimated threshold values from these estimation methods are 3.18% and 2.42%, respectively. (C) 2010 Elsevier B.V. All rights reserved.
Citation - WoS: 25
Citation - Scopus: 23
Real Interest Rates: Nonlinearity and Structural Breaks
(Physica-verlag Gmbh & Co, 2017) Corakci, Aysegul; Emirmahmutoglu, Furkan; Omay, Tolga
Real interest rate is a crucial variable that determines the consumption, investment and saving behavior of individuals and thereby acts as a key policy tool that the central banks use to control the economy. Although many important theoretical models require the real interest rates to be stationary, the empirical evidence accumulated so far has not been able to provide conclusive evidence on the mean reverting dynamics of this variable. To resolve this puzzle we re-investigate the stochastic nature of the real interest rates by developing unit root tests for nonlinear heterogeneous panels where the alternative hypothesis allows for a smooth transition between deterministic linear trends around which stationary asymmetric adjustment may occur. When the newly developed panel unit root tests are applied to the real interest rates of the 17 OECD countries, we were able to uncover overwhelming empirical support in favor of mean reversion in the short-run and long-run real interest rates. Therefore, these results show that the conclusions drawn from a miss-specified test that ignores the presence of either nonlinearity, structural breaks or cross sectional dependence can give quite misleading results about the stochastic behavior of the real interest rates.
Citation - WoS: 53
Citation - Scopus: 58
Reexamining the Ppp Hypothesis: a Nonlinear Asymmetric Heterogeneous Panel Unit Root Test
(Elsevier, 2014) Omay, Tolga; Emirmahmutoglu, Furkan
In this study, we re-examine the PPP hypothesis in the light of the new developments in the unit root testing literature. The recent theoretical findings have pointed out that the real exchange rate series exhibit asymmetric nonlinear behavior. A unit root test applied to analyze the PPP hypothesis therefore, should also take into account this asymmetry inherent in the real exchange rate. Different unit root tests that consider the presence of these data features have been developed in the time series literature. However, a true attempt to test the PPP hypothesis should take a panel data approach. To this end, we propose a nonlinear heterogeneous panel unit root test where the alternative hypothesis allows for symmetric or asymmetric exponential smooth transition autoregressive nonlinearity and provide its finite sample properties. We apply our test to the real exchange rates of the 15 European Union countries against the US dollar. While the results of the linear and symmetric nonlinear heterogeneous panel unit root tests are against the PPP hypothesis, the asymmetric nonlinear heterogeneous panel test that we propose gives support for the PPP hypothesis as expected. Therefore, the conclusions drawn from the linear panel unit root tests or the nonlinear panel unit root tests that do not take asymmetry into account might be misleading. (C) 2014 Elsevier B.V. All rights reserved.
Citation - Scopus: 1
The Relationship Between Inflation, Output Growth, and Inflation Uncertainty: Panel Data Evidence From Selected Industrial Countries
(Nova Science Publishers, Inc., 2012) Omay, T.; Omay, Tolga; Eruygur, A.; Çankaya Meslek Yüksekokulu
In this chapter, we have examined the causal relationships among the inflation rate, output growth rate, and inflation uncertainty for a panel of industrialized countries. For this purpose, we have estimated a PANEL-GARCH model for inflation rate and performed Panel-causality tests using conditional standard deviations of inflation to proxy nominal uncertainty. The relationships among inflation, output growth, and inflation uncertainty have been investigated extensively in the empirical literature for developed countries (e.g., Grier and Perry 1998; Davis and Kanago, 2000; Fountas et al. 2006; Fountas and Karanasos 2007). Our main contribution is to extend the analysis conducted by these studies to a group of developed countries using panel data techniques. The panel Granger test results have showed that the Friedman-Ball hypothesis is not supported by data when applied to the group of countries included in this chapter. This has led us to conclude that a threshold level of inflation does exist before the Friedman- Ball hypothesis applies. On the other hand, the reported test results have provided empirical support for the Cukierman-Meltzer (1986) hypothesis that inflation uncertainty raises the inflation rate in the group of industrialized countries under investigation. Our findings regarding the causal relationship between inflation uncertainty and output growth report a bidirectional relationship between these two variables. While output growth leads to an increase in inflation uncertainty at first lag, this effect is found to be insignificant at fourth lags. However, inflation uncertainty is found to be detrimental for real growth uniformly across the lags considered. Finally, a negative bidirectional causal relation was detected between output growth and inflation. © 2012 by Nova Science Publishers, Inc. All rights reserved.
Citation - WoS: 20
Citation - Scopus: 23
The Relationship Between Inflation, Output Growth, and Their Uncertainties: Evidence From Selected Cee Countries
(M E Sharpe inc, 2011) Omay, Tolga; Hasanov, Mubariz
In this paper, we examine causal relationships between inflation rate, output growth rate, inflation uncertainty, and output uncertainty for ten Central and Eastern European transition countries. For this purpose, we estimate a bivariate GARCH model that includes output growth and inflation rates for each country. Then we use conditional standard deviations of inflation and output to proxy nominal and real uncertainty, respectively, and perform Granger causality tests. Our results suggest that inflation rate induces uncertainty about both inflation rate and output growth rate, which is detrimental to real economic activity. At the same time, we find that output growth rate reduces macroeconomic uncertainty in some countries. In addition, we also examine and discuss causal relationships between the remaining variables.
Citation - WoS: 8
Citation - Scopus: 9
The Relationship Between Inflation, Output Growth, and Their Uncertainties: Nonlinear Multivariate Garch-M Evidence
(Economics Bulletin, 2011) Omay, Tolga; Omay, Tolga; Çankaya Meslek Yüksekokulu
In this paper, we propose a nonlinear multivariate GARCH-M model. We have illustrated the actual modelling by applying the models to inflation and output growth variables and found that the effects of real and nominal uncertainties are regime-dependent.
Citation - WoS: 4
Citation - Scopus: 5
Solving Technological Change Model by Using Fractional Calculus
(Springer, 2009) Omay, Tolga; Baleanu, Dumitru
Fractional calculus is a generalization of classical calculus, which is a generalization of ordinary differentiation and integration to arbitrary order, and has recently been used in various fields like physics, engineering, biology, and finance. By applying fractional calculus to Romer's Technological Change Model, we introduce this new method to the field of economics and obtain a generalized solution for the model.
Citation - WoS: 151
Citation - Scopus: 164
Testing for Unit Root in Nonlinear Heterogeneous Panels
(Elsevier Science Sa, 2009) Ucar, Nuri; Omay, Tolga
We develop unit root tests for nonlinear heterogeneous panels where the alternative hypothesis is an exponential smooth transition (ESTAR) model, and provide their small sample properties. We apply our tests for investigating the income convergence hypothesis in the OECD sample. (C) 2009 Published by Elsevier B.V.