Omay, Tolga
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T.,Omay
Omay, Tolga
O., Tolga
Tolga, Omay
Omay,T.
O.,Tolga
T., Omay
Omay T.
Omay, Tolga
O., Tolga
Tolga, Omay
Omay,T.
O.,Tolga
T., Omay
Omay T.
Job Title
Profesor Doktor
Email Address
tolga.omay@atilim.edu.tr
ORCID ID
Scopus Author ID
Turkish CoHE Profile ID
Google Scholar ID
WoS Researcher ID
Scholarly Output
56
Articles
51
Citation Count
309
Supervised Theses
2
56 results
Scholarly Output Search Results
Now showing 1 - 10 of 56
Article Citation Count: 38Sharp and smooth breaks in unit root testing of renewable energy consumption: The way forward(International Research Center for Energy and, 2018) Omay, Tolga; Omay,T.; Roubaud,D.; Economics[No abstract available]Article Citation Count: 0HYSTERESIS HYPOTHESIS VS. STRUCTURALIST VIEW IN CANADA: A NEW TEST FOR THE SHARP BREAK AND SMOOTH SHIFT(Acad Economic Studies, 2021) Omay, Tolga; Belke, Murat; Omay, Tolga; EconomicsWe have investigated the hysteresis hypothesis using a newly proposed unit root test which considers both sharp breaks and smooth shifts in its testing process for Canada during the period 1960-2019 in this study. The so-called unit root test allows researchers control for sharp breaks such as crises, smooth shifts such as nonlinearities, simultaneously. In proposing this highly complex trend structure, we are also proposing a new way for the macroeconomic theorist to model the unemployment rate following the structuralist view. It takes into account the structural breaks and possible nonlinearities as form of smooth shifts which leads to a new form of structuralist view. The empirical results display that the unemployment rates in Canada follow a non-hysteresis path under the presence of sharp and smooth structural breaks.Article Citation Count: 2Examining the non-linear stochastic behavior of the European energy market: evidence from nonlinear unit root tests(Taylor & Francis inc, 2022) Omay, Tolga; Omay, Tolga; Sahin, Eyyup Ensari; EconomicsStock market efficiency has been one of the most investigated topics of the last century. Knowing the efficiency of a market has major implications for both investors and policymakers, as a perfectly efficient market eliminates any arbitrage opportunity and the possibility of actually beating the market. For this reason, this study aims to examine the weak-form market efficiency of the European energy markets using linear and nonlinear unit root tests for the period covering February 2012 to April 2021. The results indicated that while the Augmented Dickey-Fuller test captured the stationarity in only Austria's Oil, and Gas index, using nonlinear tests showed stationarity in 17 of the 20 indices tested. Overall, the European Energy Market can be considered inefficient under the weak form of the Efficient Market Hypothesis. Therefore, there is an indication of profitable arbitrage opportunities among energy stocks. Signs of stationarity also suggest that shocks to energy stocks will have temporary effects. Energy markets of Austria, Finland, France, Greece, Italy, Netherlands, Russia, Spain, Sweden, and the United Kingdom, for this reason, could benefit from policy changes to support increased information flow to achieve more transparency and utilize better trading technologies.Conference Object Citation Count: 0Asymmetric Effects of Credit Growth on the Current Account Balance: Panel Data Evidence(Springer Science and Business Media B.V., 2019) Ekinci, Mehmet Fatih; Omay,T.; Omay, Tolga; EconomicsExpanding current account balances (both surpluses and deficits) prior to the global economic crisis dominated academic and policy debates over the past decade. Understanding the role of credit growth on the current account balance has become a priority particularly with the rebalancing experience in the post-crisis period. In this study, we adopt a comprehensive framework by constructing an empirical model that accommodates asymmetric adjustments of current account balance to the changes in the total and household credit growth. We consider the asymmetric effects in two dimensions. When we discriminate between credit expansion and contraction episodes, our results show that credit growth has a stronger negative impact on the current account balance during credit expansion periods. Furthermore, negative effects of total and household credit growth on the current account balance are more pronounced during current account deficit episodes. © 2019, Springer Nature Switzerland AG.Article Citation Count: 1Controlling Heterogeneous Structure of Smooth Breaks in Panel Unit Root and Cointegration Testing(Springer, 2023) Omay, Tolga; Iren, Perihan; EconomicsThis study aims to show the consequences of a restrictive homogeneity assumption of frequency in heterogeneous panel unit root and cointegration testing with Flexible Fourier Form. For this purpose, we use a simple panel unit root and residual based cointegration test with Flexible Fourier Form in a heterogeneous frequency setting using a bootstrap algorithm. The power of the test statistics and empirical analysis results indicate that failing to take into account a heterogeneous frequency may lead to misleading inferences, thereby leading to misspecified tests and erroneous conclusions concerning the stochastic behavior of the data in the panel sample.Article Citation Count: 18Testing for Unit Roots in Dynamic Panels with Smooth Breaks and Cross-Sectionally Dependent Errors(Springer, 2018) Omay, Tolga; Hasanov, Mubariz; Shin, Yongcheol; EconomicsWe develop the extended unit root testing procedure for dynamic panels characterised by slowly moving trends (SMT) and cross-section dependence (CSD). We allow SMT to follow the smooth logistic transition function and the components error terms to contain the unobserved common factors. We propose the two panel unit root test statistics, one derived by the extended common correlated effects (CCE) estimator and the other based on the Sieve bootstrap. We have conducted extensive simulation exercises and document that the failure to take into account SMT and CSD may lead to misleading inference. On the other hand, we find that both bootstrap and CCE-based tests maintain good power properties in small samples in the presence SMT and CSD. We apply our proposed tests to real interest rates for 17 OECD countries and find overwhelming evidence in favour of the Fisher hypothesis.Article Citation Count: 6Is real per capita state personal income stationary? New nonlinear, asymmetric panel-data evidence(Wiley, 2020) Omay, Tolga; Gupta, Rangan; Miller, Stephen M.; Omay, Tolga; EconomicsThis paper re-examines the stochastic properties of U.S. state real per capita personal income, using new panel unit-root procedures. The new developments incorporate non-linearity, asymmetry, and cross-sectional correlation within panel-data estimation. Including nonlinearity and asymmetry finds that 43 states exhibit stationary real per capita personal income whereas including only nonlinearity produces 42 states that exhibit stationarity. Stated differently, we find that two states exhibit nonstationary real per capita personal income when considering nonlinearity, asymmetry, and cross-sectional dependence.Article Citation Count: 11Environmental Kuznets Curve: Non-Linear Panel Regression Analysis(Springer, 2020) Omay, Tolga; Omay, Tolga; Yildirim, Julide; Kose, Nezir; EconomicsThis study presents an analysis of the relationship between per capita CO2 emissions as an environmental degradation indicator and per capita gross domestic product (GDP) as an economic growth indicator within the framework of the Environmental Kuznets Curve (EKC). For this purpose, non-linear panel models are estimated for the Annex I countries, non-Annex countries, and whole parties with respect to data availability of the United States Convention on Climate Change (UNFCCC) for the period 1960-2012. The empirical results of the panel smooth transition models (PSTR) show that the environmental deterioration rises in the first phase of growth for all data sets. Afterwards, the environmental degradation cannot be prevented, but the increase in the amount of environmental degradation decreases. The findings of this study give an insight regarding the differential environmental impact of economic growth between developed and developing countries. While the validity of a traditional EKC relation regarding the CO2 emissions cannot be affirmed for any group of countries in our sample, empirical results indicate the existence of multiple regimes where economic growth hampers environmental quality, but its severity decreases at each consecutive regime.Conference Object Citation Count: 0Nonlinearity in Emerging European Markets: Pre and Post Crisis Periods(Springer Science and Business Media B.V., 2019) Omay, Tolga; Omay,T.; EconomicsInvestigating the efficiency of emerging markets has been a popular research trend in the past decade, showing implications on both the economy and the policies of the countries in question. Market efficiency, in other words, informational efficiency, states that if markets are fully efficient, then all information is instantly reflected the prices of stocks. However, there are many arguments for and against this theory, especially on the discussions of the 2008 Global Financial Crisis. These past studies are seen to be showing mixed results. It is important the note that there is a nonlinear movement among the stock prices within stock markets and this needs to be incorporated in the tests that are used to measure their efficiency in order to obtain more accurate results. Therefore, in this study, we have tested the weak form efficiency of the emerging markets located in Europe, namely, Czech Republic, Greece, Hungary, Poland, Turkey, and Russia. Effects of the 2008 Global Financial Crisis were put forward by taking two different time periods (Pre: November 2005–September 2008 and Post: October 2008–February 2019—Crisis) and applying newly developed nonlinear unit root tests. Results of the study supported previous research and showed that the efficiency of most markets changed in the post-crisis period from efficient to inefficient. © 2019, Springer Nature Switzerland AG.Article Citation Count: 11Smooth Break Detection and De-Trending in Unit Root Testing(Mdpi, 2021) Omay, Tolga; Omay, Tolga; Shahzad, Syed Jawad Hussain; Nor, Safwan Mohd; EconomicsThis study explores the methods to de-trend the smooth structural break processes while conducting the unit root tests. The two most commonly applied approaches for modelling smooth structural breaks namely the smooth transition and the Fourier functions are considered. We perform a sequence of power comparisons among alternative unit root tests that accommodate smooth or sharp structural breaks. The power experiments demonstrate that the unit root tests utilizing the Fourier function lead to unexpected results. Furthermore, through simulation studies, we investigate the source of such unexpected outcomes. Moreover, we provide the asymptotic distribution of two recently proposed unit root tests, namely Fourier-Augmented Dickey-Fuller (FADF) and Fourier-Kapetanios, Shin and Shell (FKSS), which are not given in the original studies. Lastly, we find that the selection of de-trending function is pivotal for unit root testing with structural breaks.
