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Article Citation - WoS: 1Citation - Scopus: 1Testing for Unit Roots in Nonlinear Dynamic Heterogeneous Panels With Logistic Smooth Breaks(Mdpi, 2023) Omay, Tolga; Ucar, NuriIn this study, we investigate the validity of the purchasing power parity (PPP) proposition for 34 European and selected global countries. For this purpose, we propose a new unit root test for cross-sectionally dependent heterogeneous panels that allows for gradual structural breaks and symmetric nonlinear adjustment toward the equilibrium level. The alternative hypothesis stationary is obtained by symmetric adjustment due to exponential smooth transition autoregression (ESTAR) around a nonlinear trend. Moreover, we provide small sample properties extensively for the newly proposed test. Hence, this alternative hypothesis has been proven to characterize real exchange rate data (REER) correctly. Thus, the newly proposed tests provide an essential basis for modeling the REER series correctly. Finally, we also derive the approximate asymptotic distribution of the proposed tests using new techniques.Article Citation - WoS: 35Citation - Scopus: 36Structural Break, Nonlinearity and Asymmetry: a Re-Examination of Ppp Proposition(Routledge Journals, Taylor & Francis Ltd, 2018) Omay, Tolga; Emirmahmutoglu, Furkan; Hasanov, MubarizIn this study, we examine the validity of the PPP proposition for 28 European countries. For this purpose, we propose a new unit root test procedure that allows for both gradual structural breaks and asymmetric nonlinear adjustment towards the equilibrium level. Small-sample properties of the new tests are examined through Monte-Carlo simulations. The simulation results suggest that the new tests have satisfactory size and power properties. We then apply these new tests along with other unit root tests to examine stationarity properties of real exchange rate series of the sample countries. Our tests reject the null of unit root in more cases when compared to alternative tests. Overall, we find that the PPP proposition holds in majority of the European countries examined in this article.Article Citation - WoS: 19Citation - Scopus: 17Testing Ppp Hypothesis Under Temporary Structural Breaks and Asymmetric Dynamic Adjustments(Routledge Journals, Taylor & Francis Ltd, 2020) Omay, Tolga; Shahbaz, Muhammed; Hasanov, MubarizWe test the empirical validity of the PPP proposition under temporary structural breaks and dynamic nonlinear adjustments. Although several testing procedures have recently been proposed in the existing literature to investigate stochastic properties of the series under gradual breaks and nonlinear adjustments, none of these tests are compatible with the PPP proposition. Therefore, we propose new testing procedures that restrict the break to be temporary while simultaneously allowing for asymmetric dynamic nonlinear adjustment towards equilibrium. Using these newly proposed tests, we test stationarity of real exchange rate of 24 OECD countries vis-a-vis USA, and find support in favour of PPP proposition in majority of the countries.
