A multivariate distance nonlinear causality test based on partial distance correlation: a machine learning application to energy futures

This paper proposes a multivariate distance nonlinear causality test (MDNC) using the partial distance correlation in a time series framework. Partial distance correlation as an extension of the Brownian distance correlation calculates the distance correlation between random vectors X and Y controlling for a random vector Z. Our test can detect nonlinear lagged relationships between time series, and when integrated with machine learning methods it can improve the forecasting power. We apply our method as a feature selection procedure and combine it with the support vector machine and random forests algorithms to study the forecast of the main energy financial time series (oil, coal, and natural gas futures). It shows substantial improvement in forecasting the fuel energy time series in comparison to the classical Granger causality method in time series.     

Are the interdependence characteristics of the US and Canadian energy equity sectors nonlinear and asymmetric?

Nonlinear, symmetric, and asymmetric dependence characteristics in energy equity sectors matter to portfolio investors and risk managers because of the risks and diversification opportunities they entail. Specifically, nonlinear dependence dynamics between assets are harder to predict, monitor, and manage, and can make investment positions go wrong unexpectedly. In this paper, we investigate whether the dependence dynamics of US and Canadian large-capitalized energy equity portfolios are nonlinear, symmetric, or asymmetric. We draw our results by implementing a robust copula approach based on time-varying parameter copulas and vine copula methods. Both time varying parameter and vine-copula methods indicate that the Canadian energy sector portfolio is driven by nonlinear negative tail asymmetric dependence during the global financial crisis and when the full sample period is employed. On the other hand, it displays nonlinear symmetric dependence during the oil price crisis, implying the need for close monitoring and rebalancing and a more continuous assessment of long investment positions. The US energy sector portfolio is driven by positive tail asymmetric dependence, and by symmetric dependence dynamics during crisis and non-crisis periods.     

Testing PPP hypothesis under temporary structural breaks and asymmetric dynamic adjustments

ABSTRACT

We 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-à-vis USA, and find support in favour of PPP proposition in majority of the countries.     

互联网发展与区域创新能力非线性关系研究

党的十九大报告要求全力推动互联网、大数据、人工智能与实体经济深度融合。在此背景下，明晰互联网与区域创新能力关系至关重要。基于2006-2017年中国内地30个省区市面板数据，运用门槛面板回归技术，全面探讨了互联网发展与区域创新能力间的非线性关系。研究结果表明：互联网发展对区域创新能力存在边际报酬递增的正向非线性影响，且在政府支持环境下两者存在正向、边际报酬递增的非线性关系，但在对外开放环境下，两者存在正向U型关系。进一步研究发现，互联网发展对不同创新主体的创新能力存在异质性双门槛效应，如对高校、企业呈现出正向U型影响，而对研发机构表现为正向的边际效率递减规律。依据该结论提出具有针对性的差异化“互联网+创新能力”融合策略。     

Oil price shocks and economic growth: The volatility link

This paper shows that oil shocks impact economic growth primarily through the conditional variance of growth. Our comparison of models focuses on density forecasts. Over a range of dynamic models, oil shock measures and data, we find a robust link between oil shocks and the volatility of economic growth. We then develop a new measure of oil shocks and show that it is superior to existing measures; it indicates that the conditional variance of growth increases in response to an indicator of the local maximum oil price exceedance. The empirical results uncover a large pronounced asymmetric response of the growth volatility to oil price changes. The uncertainty about future growth is considerably lower than with a benchmark AR(1) model when no oil shocks are present.     

Effects of monetary policy on the REIT returns: Evidence from the United Kingdom

In this paper, we analyze whether a monetary policy based on three main variables (inflation, money supply, and output gap) has a nonlinear impact on real estate investment trust (REIT) markets. In addition, we extend our analysis to examine whether these monetary policy components impact the possibility of boom and bust regimes occurring in the market. Empirically, we propose different Markov-switching model variants to determine the nonlinear time-varying impact of monetary policy on the REIT market. Our results show the monetary policy environment is supposed to affect, on one hand, the REIT returns and, on the other hand, the possibility of boom and bust markets. We prove that expansionary monetary policy has an impact only in the case of boom market. However, an increase in the inflation rate decreases the probability of remaining in the bust regime. As a consequence, we have already outlined several monetary transmission mechanisms that show house prices to have important effects on aggregate demand. Our results confirm that REIT markets are not efficient.     

解非线性电路稳态响应的一种有效算法

本文提供一种计算非线性电路的稳态响应的有效算法,在多频信号激励的强迫振荡电路和耦合振荡电路都可使用。该方法可称为“代换算法”。因为,它每一步的变量都是用残留误差的各个频率分量解关联时不变电路,该电路是用“松弛法”将时变电路转换而来。此算法非常简单而有效,并且可应用于各种非线性电路。     

Convergence analysis and optimal strike choice for static hedges of general path-independent pay-offs

In this paper, we propose a new algorithm to find the optimal static replicating portfolios for general path-independent nonlinear pay-off functions and give an estimate for the rate of convergence that is absent in the literature. We choose the static replication by designing an adaptation function arising in the error bound between the nonlinear pay-off function and the linear spline approximation and derive the equidistribution equation for selecting the optimal strikes. The numerical tests for variance swaps, swaptions, static quadratic hedges and also for a jump-diffusion process, allowing for the default of the underlying asset, show that the proposed iterative equidistribution equation algorithm is simple, fast and accurate. The paper generalizes and improves the results on static replication and approximation in the literature.     

Solvability of perturbation solutions in DSGE models

We prove that the undetermined Taylor series coefficients of local approximations to the policy function of arbitrary order in a wide class of discrete time dynamic stochastic general equilibrium (DSGE) models are solvable by standard DSGE perturbation methods under regularity and saddle point stability assumptions on first order approximations. Extending the approach to nonstationary models, we provide necessary and sufficient conditions for solvability, as well as an example in the neoclassical growth model where solvability fails. Finally, we eliminate the assumption of solvability needed for the local existence theorem of perturbation solutions, complete the proof that the policy function is invariant to first order changes in risk, and attribute the loss of numerical accuracy in progressively higher order terms to the compounding of errors from the first order transition matrix.     

How Islamic are Islamic banks? A non-linear assessment of Islamic rate – conventional rate relations

In this paper, we perform a non-linear assessment of Islamic rate – conventional rate relations for the case of Malaysia. Using monthly data covering the period January 1999 to November 2016, we find strong evidence supporting non-linear reactions of the Islamic investment rates to conventional rates in the long run and/or short-run for all matched maturities. More precisely, the Islamic investment rates exhibit faster upward movement (slower downward movement) in responses to conventional deposit rate increases (decreases). The asymmetric pricing behaviour of Islamic banks however tends to weaken as maturity lengthens. Accordingly, we infer that Islamic banks do not rigidly peg their investment deposit rates to conventional deposit rates as some have claimed in questioning the Islamicity of Islamic banks.