Tolga Omay

THE ENDOGENOUS AND NON‐LINEAR RELATIONSHIP BETWEEN TERRORISM AND ECONOMIC PERFORMANCE: TURKISH EVIDENCE

This paper investigates the macroeconomic effects of terror by using a novel data set from Turkey for the period of 1987:1 to 2004:4. This research contributes to the literature by controlling for the possible non‐linear and endogenous relationship between political conflict and economic activity. Empirical evidence from both linear and non‐linear models confirms that terrorism has a large significant negative impact on economic activity. Finally, the results from the non‐linear model show that the impact of terrorism on the aggregate economy is more severe during expansionary periods, and that the impact of economic activity on terrorism is significant only in recessionary periods.

The relationship between inflation, output growth, and their uncertainties: Evidence from selected CEE countries

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.

Nonlinearities in emerging stock markets: evidence from Europe's two largest emerging markets

Recent developments in time series analysis allow proper modelling of nonlinearities in economic and financial variables. A growing body of research was dedicated to investigation of potential nonlinearities in conditional mean of many economic and financial variables, mainly concentrating in developed economies. However, nonlinearities in financial variables in developing economies have not been fully examined yet. In this article we investigate potential nonlinearity and cyclical behaviour of stock returns in Europes two largest emerging stock markets, mainly in the Greek and Turkish stock markets. Specifically, we use STAR family models, which allow to model nonlinearities in the conditional mean, for modelling monthly returns on stock exchange indices of the Athens Stock Exchange and Istanbul Stock Exchange. Although we find no nonlinearity in conditional variance, we do find strong evidence in favour of nonlinear adjustment of stock returns. It is found that allowing for nonlinearity in conditional mean results in a superior model and provides good out-of-sample forecasts, which contradicts to efficient market hypothesis.

The effects of inflation uncertainty on interest rates: a nonlinear approach

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.

Solving Technological Change Model by Using Fractional Calculus

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.

Terrorism and the Stock Market: A Case Study for Turkey Using STR Models

Several attempts have been made in the literature to analyze the detrimental effects of terrorist activities on the stock market. However, in neither of these studies the effects of terrorist activities on stock returns are investigated through employing nonlinear models in spite of the fact that most financial data is shown to exhibit nonlinear behaviour. This study, therefore, aims to contribute to this growing area of research by exploring the potential nonlinear effects of terrorist activities on stock returns by employing smooth transition regression (STR) models. Our results show that terrorism has a statistically significant negative effect on the stock index when the intensity of terrorist activities passes a certain threshold level. This negative effect continues for terrorist activities below this threshold level, but becomes statistically insignificant. This study by conducting the analysis within a nonlinear framework offers important insights into the investors who want to make portfolio diversification strategies against terrorism risk.

Structural break, nonlinearity and asymmetry: a re-examination of PPP proposition

ABSTRACT In 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.

The US real GNP is trend-stationary after all

ABSTRACT This article applies the Fractional Frequency Flexible Fourier Form (FFFFF) Dickey–Fuller (DF)-type unit root test on the natural logarithm of US real GNP over the quarterly period of 1875:1–2015:2, to determine whether the same is trend- or difference-stationary. While standard and Integer Frequency Flexible Fourier Form DF-type test fails to reject the null of unit root, the relatively more powerful FFFFF DF-type test provides strong evidence of the real GNP as being trend-stationary, i.e. US output returns to a deterministic log-nonlinear trend in the long run.

Economic Crisis and Investor Behaviour

This study investigates the effects of crises on domestic and foreign investors’ behaviours by utilizing a nonlinear approach. Considering the nonlinearity inherent in many financial variables, this study proposes an appropriate econometric modelling for analysing the investors’ behaviour, particularly during turbulent times. Specifically, STAR-STGARCH family models and generalized impulse response function analysis (GIRF) are employed to understand the different reactions of foreign and domestic investors at the Malaysian Stock Exchange market during the 1997 Asian crisis. The results of the model and the GIRF analysis have shown that foreign investors exhibited a herding behavior during the crisis and responded the shock more quickly than the domestic investors. When the same analysis is applied to understand the effects of the 2008 Subprime Mortgage Crisis in the Malaysian market, the behaviors of foreign and domestic investors are found to be very similar.

Is Real Per Capita State Personal Income Stationary? New Nonlinear, Asymmetric Panel-Data Evidence

This paper re-examines the stochastic properties of US 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 the 42 states that exhibit stationarity. Stated differently, we find that 2 states exhibit nonstationary real per capita personal income when considering nonlinearity, asymmetry, and cross-sectional dependence.