Omay, Tolga

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Profile URL
https://hdl.handle.net/20.500.14411/7237
Name Variants
T.,Omay
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
Main Affiliation
Economics
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Website
ORCID ID
Scopus Author ID
23978235900
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Google Scholar ID
WoS Researcher ID
GDI-4259-2022

Sustainable Development Goals

5

GENDER EQUALITY
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0

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14

LIFE BELOW WATER
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2

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10

REDUCED INEQUALITIES
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2

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3

GOOD HEALTH AND WELL-BEING
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2

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2

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0

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9

INDUSTRY, INNOVATION AND INFRASTRUCTURE
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3

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16

PEACE, JUSTICE AND STRONG INSTITUTIONS
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0

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11

SUSTAINABLE CITIES AND COMMUNITIES
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1

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8

DECENT WORK AND ECONOMIC GROWTH
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11

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13

CLIMATE ACTION
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7

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4

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0

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6

CLEAN WATER AND SANITATION
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0

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1

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15

LIFE ON LAND
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1

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17

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7

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7

AFFORDABLE AND CLEAN ENERGY
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3

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12

RESPONSIBLE CONSUMPTION AND PRODUCTION
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1

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Documents

80

Citations

1218

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20

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Documents

74

Citations

1075

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Scholarly Output

65

Articles

55

Views / Downloads

19/0

Supervised MSc Theses

4

Supervised PhD Theses

2

WoS Citation Count

435

Scopus Citation Count

503

WoS h-index

13

Scopus h-index

13

Patents

0

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0

WoS Citations per Publication

6.69

Scopus Citations per Publication

7.74

Open Access Source

32

Supervised Theses

6

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JournalCount
Applied Economics5
Computational Economics5
Springer Proceedings in Business and Economics -- 4th International Conference on Banking and Fice Perspectives, ICBFP 2019 -- 2 May 2019 through 3 May 2019 -- Famagusta -- 2737293
Mathematics3
Environmental Science and Pollution Research2
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Has files: falseSubject: Unit root

Scholarly Output Search Results

Now showing 1 - 4 of 4
  • Thumbnail Image
    Article
    Citation - WoS: 4
    Citation - Scopus: 5
    A Long-Run Convergence Analysis of Aerosol Precursors, Reactive Gases, and Aerosols in the Brics and Indonesia: Is a Global Emissions Abatement Agenda Supported?
    (Springer Heidelberg, 2023) Romero-Avila, Diego; Omay, Tolga
    This article examines the hypothesis of deterministic emissions convergence for a panel of the BRICS and Indonesia to advanced countries' emissions levels as well as to Sweden (which is a country that has clearly gone through decoupling) using a novel dataset with ten series of annual estimates of anthropogenic emissions comprising aerosols, aerosol precursor and reactive compounds, and carbon dioxide from 1820 to 2018. For that purpose, we employ four novel panel unit root tests allowing for several forms of time-dependent and state-dependent nonlinearity. The evidence supports deterministic convergence following a linear process for carbon dioxide, whereas the adjustment is asymmetric and nonlinear for carbon monoxide. Methane and nitrogen oxides exhibit logistic smooth transition converging dynamics. In contrast, black carbon, ammonia, nitrous oxide, non-methane volatile organic compounds, organic carbon, and sulfur dioxide emissions diverge. These results have implications for the abatement of greenhouse gases emissions at the global level, given the high share of emissions of the BRICS.
  • Thumbnail Image
    Article
    Citation - WoS: 6
    Citation - Scopus: 4
    Does Real Uk Gdp Have a Unit Root? Evidence From a Multi-Century Perspective
    (Routledge Journals, Taylor & Francis Ltd, 2020) Canarella, Giorgio; Gupta, Rangan; Millera, Stephen M.; Omay, Tolga
    We employ linear and nonlinear unit-root tests to examine the stationarity of five multi-century historical U.K. series of real output compiled by the Bank of England. Three series span 1270 to 2016 and two series span 1700 to 2016. These datasets represent the longest span of historical real output data available and, thus, provide the environment for which unit-root tests are most powerful. A key feature of our test is its simultaneous allowance for two types of nonlinearity: time-dependent (structural breaks) nonlinearity and state-dependent (asymmetric adjustment) nonlinearity. The key finding of the test, contrary to what other more popular nonlinear unit-root tests suggest, provides strong evidence that the main structure of the five series is a stationary process characterized by an asymmetric nonlinear adjustment and a permanent break affecting both the intercept and the trend. A major policy implication of this finding is fiscal and/or monetary stabilization policies have only temporary effects on the output levels of the United Kingdom.
  • Thumbnail Image
    Article
    Citation - WoS: 1
    Citation - Scopus: 1
    A Unit Root Test With Markov Switching Deterministic Components: A Special Emphasis on Nonlinear Optimization Algorithms
    (Springer, 2023) Omay, Tolga; Corakci, Aysegul
    In this study, we investigate the performance of different optimization algorithms in estimating the Markov switching (MS) deterministic components of the traditional ADF test. For this purpose, we consider Broyden, Fletcher, Goldfarb, and Shanno (BFGS), Berndt, Hall, Hall, Hausman (BHHH), Simplex, Genetic, and Expectation-Maximization (EM) algorithms. The simulation studies show that the Simplex method has significant advantages over the other commonly used hill-climbing methods and EM. It gives unbiased estimates of the MS deterministic components of the ADF unit root test and delivers good size and power properties. When Hamilton's (Econometrica 57:357-384, 1989) MS model is re-evaluated in conjunction with the alternative algorithms, we furthermore show that Simplex converges to the global optima in stationary MS models with remarkably high precision and even when convergence criterion is raised, or initial values are altered. These advantages of the Simplex routine in MS models allow us to contribute to the current literature. First, we produce the exact critical values of the generalized ADF unit root test with MS breaks in trends. Second, we derive the asymptotic distribution of this test and provide its invariance feature.
  • Thumbnail Image
    Article
    Citation - WoS: 6
    Citation - Scopus: 8
    Are CO2 Emissions Stationary After All? New Evidence from Nonlinear Unit Root Tests
    (Springer, 2022) Romero-Avila, Diego; Omay, Tolga
    This study applies a large battery of state-of-the-art nonlinear unit root tests to examine the stationarity properties of carbon dioxide emission series for 28 industrialized countries, five BRICS and seven transition economies over a very long horizon, in some cases over more than two and a half centuries. The application of time-dependent and state-dependent nonlinear unit root tests separately provides mixed evidence regarding the time-series properties of CO2 emissions and a high degree of variability across the different tests. However, the use of hybrid nonlinear unit root tests, combining the presence of structural breaks with symmetric or asymmetric ESTAR adjustment, leads to the rejection of the unit root hypothesis in each of the countries under study with at least one of the hybrid tests. This has important climate policy implications.