CONSTRUCTING OPTIMAL DENSITY FORECASTS FROM POINT FORECAST COMBINATIONS

Decision makers often observe point forecasts of the same variable computed, for instance, by commercial banks, IMF and the World Bank, but the econometric models used by such institutions are frequently unknown. This paper shows how to use the information available on point forecasts to compute optimal density forecasts. Our idea builds upon the combination of point forecasts under general loss functions and unknown forecast error distributions. We use real‐time data to forecast the density of US inflation. The results indicate that the proposed method materially improves the real‐time accuracy of density forecasts vis‐à‐vis those from the (unknown) individual econometric models. Copyright © 2013 John Wiley & Sons, Ltd.     

EXCHANGE RATE FUNDAMENTALS,FORECASTING, AND SPECULATION: BAYESIAN MODELS IN BLACK MARKETS

Although speculative activity is central to black markets for currency, the out‐of‐sample performance of structural models in those settings is unknown. We substantially update the literature on empirical determinants of black market rates and evaluate the out‐of‐sample performance of linear models and non‐parametric Bayesian treed Gaussian process (BTGP) models against the random walk benchmark. Fundamentals‐based models outperform the benchmark in out‐of‐sample prediction accuracy and trading rule profitability measures given future values of fundamentals. In simulated real‐time trading exercises, however, the BTGP achieves superior realized profitability, accuracy and market timing, while linear models do no better than a random walk. Copyright © 2013 John Wiley & Sons, Ltd.     

基于双自适应Lasso惩罚的随机效应分位回归模型研究

研究目标：解决随机效应分位回归模型中固定效应和随机效应系数同时估计和选择问题。研究方法：对固定效应和随机效应系数同时实施自适应Lasso惩罚,并为参数估计设计交替迭代算法。研究发现：新方法不仅对随机误差分布具有较强的稳健性,而且在不同稀疏度模型下均有着良好的表现,尤其是在高维情形时。研究创新：本文提出的方法在对模型中重要自变量进行选择的同时能够充分考虑随机效应的影响;交替迭代算法不仅有效解决了需要选择两个惩罚参数的困境,而且收敛速度快。研究价值：为实际工作者对面板数据和纵向数据的分析提供了有效的建模方法。     

Transdisciplinarity in Corporate Sustainability: Mapping the Field

Sustainability challenges are complex. So are the challenges that business firms encounter in their corresponding quest for corporate sustainability. Given this complexity, there is a need for new approaches to corporate sustainability management research. We discuss transdisciplinarity as such a novel approach in three steps. After showing that specialization is the primary conventional response to increasing complexity, we first briefly compare how inter‐, multi‐ and transdisciplinarity reintegrate decentralized, specialized knowledge. The second step describes how the emerging sustainability science has recently advanced the transdisciplinary methodology. Based on the two dimensions of interdisciplinarity and academia–practice collaboration, we third generate a framework for mapping existing research approaches in terms of their transdisciplinary qualities. We use this framework to identify room for novel methodologies in sustainability management research. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment.     

FIRM HETEROGENEITY,PERSISTENT AND TRANSIENT TECHNICAL INEFFICIENCY: A GENERALIZED TRUE RANDOM‐EFFECTS model

This paper considers a panel data stochastic frontier model that disentangles unobserved firm effects (firm heterogeneity) from persistent (time‐invariant/long‐term) and transient (time‐varying/short‐term) technical inefficiency. The model gives us a four‐way error component model, viz., persistent and time‐varying inefficiency, random firm effects and noise. We use Bayesian methods of inference to provide robust and efficient methods of estimating inefficiency components in this four‐way error component model. Monte Carlo results are provided to validate its performance. We also present results from an empirical application that uses a large panel of US commercial banks. Copyright © 2012 John Wiley & Sons, Ltd.     

SEQUENTIAL MONTE CARLO SAMPLING FOR DSGE MODELS

We develop a sequential Monte Carlo (SMC) algorithm for estimating Bayesian dynamic stochastic general equilibrium (DSGE) models; wherein a particle approximation to the posterior is built iteratively through tempering the likelihood. Using two empirical illustrations consisting of the Smets and Wouters model and a larger news shock model we show that the SMC algorithm is better suited for multimodal and irregular posterior distributions than the widely used random walk Metropolis–Hastings algorithm. We find that a more diffuse prior for the Smets and Wouters model improves its marginal data density and that a slight modification of the prior for the news shock model leads to drastic changes in the posterior inference about the importance of news shocks for fluctuations in hours worked. Unlike standard Markov chain Monte Carlo (MCMC) techniques; the SMC algorithm is well suited for parallel computing. Copyright © 2014 John Wiley & Sons, Ltd.     

Replicating the Results in ‘A New Model of Trend Inflation’ Using Particle Markov Chain Monte Carlo

An article by Chan et al. ( 2013 ) published in the Journal of Business and Economic Statistics introduces a new model for trend inflation. They allow the trend inflation to evolve according to a bounded random walk. In order to draw the latent states from their respective conditional posteriors, they use accept–reject Metropolis–Hastings procedures. We reproduce their results using particle Markov chain Monte Carlo (PMCMC), which approaches drawing the latent states from a different technical point of view by relying on combining Markov chain Monte Carlo and sequential Monte Carlo methods. To conclude: we are able to reproduce the results of Chan et al. ( 2013 ). Copyright © 2015 John Wiley & Sons, Ltd.     

DOES CORESIDENCE IMPROVE AN ELDERLY PARENT'S HEALTH?

It is generally believed that intergenerational coresidence by elderly parents and adult children provides old‐age security for parents. Although such coresidence is still the most common living arrangement in many countries, empirical evidence of its benefits to parental health is scarce. Using Indonesian data and a program evaluation technique that accounts for non‐random selection and heterogeneous treatment effect, we find robust evidence of a negative coresidence effect. We also find heterogeneity in the coresidence effect. Socially active elderly parents are less likely to be in coresidence, and when they do live with a child they experience a better coresidence effect. Copyright © 2013 John Wiley & Sons, Ltd.     

A Unifying Framework for Marginalised Random‐Intercept Models of Correlated Binary Outcomes

We demonstrate that many current approaches for marginal modelling of correlated binary outcomes produce likelihoods that are equivalent to the copula‐based models herein. These general copula models of underlying latent threshold random variables yield likelihood‐based models for marginal fixed effects estimation and interpretation in the analysis of correlated binary data with exchangeable correlation structures. Moreover, we propose a nomenclature and set of model relationships that substantially elucidates the complex area of marginalised random‐intercept models for binary data. A diverse collection of didactic mathematical and numerical examples are given to illustrate concepts. Copyright © 2013 John Wiley & Sons, Ltd.     

一种基于四分法噪声检测的开关中值滤波算法

为了精确的检测出图像中的脉冲噪声并滤除,提出一种基于四分法噪声检测的开关中值滤波算法。该算法使用一种新的检测方法将噪声检测窗口内的像素按灰度值大小进行排序,并且通过差分方法划分出高、低阶噪声块和高、低阶信号块四部分。当待测像素属于高、低阶信号块时将其视为信号点,否则,根据噪声块与信号块内像素比例关系就可认定其为噪声点或可能噪声点,若为可能噪声点,则需扩展检测窗口重新检测。对确定噪声点,取滤窗内信号点的中值作为滤波输出。实验证明该算法对脉冲噪声有较强的抑制作用。     

Behavioral Decision Making in the (Q,R) Purchasing Model: An Experimental Study

This paper presents and analyzes the results of a decision‐making experiment in inventory management under uncertainty. The experiment included 81 participants who played the role of a small car importer facing random demand as in the (Q,R) model. The results show strong evidence of learning and convergence, and the average reorder point (R) closely approaches the optimal level for maximizing profits. However, the participants' decisions are still biased by realizations of extreme values of demand and loss of potential sales. We argue that participants are affected by recency, loss aversion, and, possibly, their own risk aversion. Copyright © 2013 John Wiley & Sons, Ltd.     

FORECASTING DISCONNECTED EXCHANGE RATES

The inability of empirical models to forecast exchange rates has given rise to the belief that exchange rates are disconnected from macroeconomic fundamentals. This paper addresses the potential disconnect by endogenously selecting forecast models from a broad set of fundamentals. The procedure shows that exchange rates are not disconnected from fundamentals, but fundamentals vary in their predictive content at different forecast horizons and for different currencies. Performing model selection out‐of‐sample is challenging. At short horizons, the method cannot outperform a random walk, although the performance is improved at long horizons. These findings are confirmed across currencies and forecast evaluation methods. Copyright © 2013 John Wiley & Sons, Ltd.     

Identification and Estimation of Online Price Competition With an Unknown Number of Firms

This paper considers identification and estimation of a general model for online price competition. We show that when the number of competing firms is unknown the underlying parameters of the model can still be identified and estimated employing recently developed results on measurement errors. We illustrate our methodology using UK data for personal digital assistants and employ the estimates to simulate competitive effects. Our results reveal that heightened competition has differential effects on the prices paid by different consumer segments. Copyright © 2015 John Wiley & Sons, Ltd.     

ESTIMATION OF CENSORED PANEL‐DATA MODELS WITH SLOPE HETEROGENEITY

This paper considers estimation of censored panel‐data models with individual‐specific slope heterogeneity. The slope heterogeneity may be random (random slopes model) or related to covariates (correlated random slopes model). Maximum likelihood and censored least‐absolute deviations estimators are proposed for both models. The estimators are simple to implement and, in the case of maximum likelihood, lead to straightforward estimation of partial effects. The rescaled bootstrap suggested by Andrews (Econometrica 2000; 68 : 399–405) is used to deal with the possibility of variance parameters being equal to zero. The methodology is applied to an empirical study of Dutch household portfolio choice, where the outcome variable (portfolio share in safe assets) has corner solutions at zero and one. As predicted by economic theory, there is strong evidence of correlated random slopes for the age profiles, indicating a heterogeneous age profile of portfolio adjustment that varies significantly with other household characteristics. Copyright © 2013 John Wiley & Sons, Ltd.     

Modelling low income transitions

We examine the determinants of low income transitions using first‐order Markov models that control for initial conditions effects (those found to be poor in the base year may be a non‐random sample) and for attrition (panel retention may also be non‐random). The model estimates, derived from British panel data for the 1990s, indicate that there is substantial state dependence in poverty, separate from persistence induced by heterogeneity. We also provide estimates of low income transition rates and lengths of poverty and non‐poverty spells for persons of different types. Copyright © 2004 John Wiley & Sons, Ltd.     

Unemployment and liquidity constraints

We present a dynamic framework for the interaction between borrowing (liquidity) constraints and deviations of actual hours from desired hours, both measured by discrete‐valued indicators, and estimate it as a system of dynamic binary and ordered probit models with panel data from the Panel Study of Income Dynamics. We analyze a household's propensity to be liquidity constrained by means of a dynamic binary probit model. We analyze qualitative aspects of the conditions of employment, namely whether the household head is involuntarily overemployed, voluntarily employed, or involuntarily underemployed or unemployed, by means of a dynamic ordered probit model. We focus on the possible interaction between the two types of constraints. We estimate these models jointly using maximum simulated likelihood, where we allow for individual random effects along with an autoregressive process for the general error term in each equation. A novel feature of our method is that it allows for the random effects to be correlated with regressors in a time‐invariant fashion. Our results provide strong support for the basic theory of constrained behavior and the interaction between liquidity constraints and exogenous constraints on labor supply. Copyright © 2007 John Wiley & Sons, Ltd.     

A simple framework for analysing bull and bear markets

Bull and bear markets are a common way of describing cycles in equity prices. To fully describe such cycles one would need to know the data generating process (DGP) for equity prices. We begin with a definition of bull and bear markets and use an algorithm based on it to sort a given time series of equity prices into periods that can be designated as bull and bear markets. The rule to do this is then studied analytically and it is shown that bull and bear market characteristics depend upon the DGP for capital gains. By simulation methods we examine a number of DGPs that are known to fit the data quite well—random walks, GARCH models, and models with duration dependence. We find that a pure random walk provides as good an explanation of bull and bear markets as the more complex statistical models. In the final section of the paper we look at some asset pricing models that appear in the literature from the viewpoint of their success in producing bull and bear markets which resemble those in the data. Copyright © 2002 John Wiley & Sons, Ltd.     

A Transdisciplinary Exploratory Model of Corporate Responses to the Challenges of Environmental Sustainability

Global surveys of business leaders identify the environment as a major issue of concern, but uncertainties about how to address the challenges of environmental sustainability are cited as a significant inhibitor to business responses. Persistent levels of corporate uncertainty in this domain may be due to the complexity of issues and difficulties in meaningfully capturing this complexity. Calls have been made for new ways to produce knowledge about complex societal challenges, including environmental sustainability. This paper aims to reduce business uncertainties and to stimulate business and research initiatives. The paper describes a field study of a global corporation's pioneering responses to environmental sustainability. The study highlights academic and practitioner collaboration to generate, transfer and implement new knowledge through an innovative research approach. The outcome is a transdisciplinary, exploratory model, presenting a progression of integrated activities and processes within eight categories of corporate responses. Implications for research and practice are considered. Copyright © 2013 John Wiley & Sons, Ltd and ERP Environment.     

基于混合智能算法的仓库有限容量下随机存贮模型

针对仓库容量有限条件下的随机存贮管理问题,通过找出商品在销售进货过程中会出现的全部可能,确定得到总损失最小的方法,然后以最优订货点作为决策变量并确定约束条件,建立优化决策模型。采用基于随机模拟的混合智能算法对该决策模型进行求解。对模型中的不确定函数进行随机模拟,使用由其产生的一组输入输出数据来训练神经网络对该不确定函数进行逼近,然后将该神经网络作为适应度函数嵌套于遗传算法中,最后应用遗传算法解得模型的最优解。通过计算机仿真得到所需要的最优方案。实验表明,文中提出的基于混合智能算法的仓库随机存贮模型,较好地解决了实际应用中的仓库容量有限的随机存贮问题,具有很强的普遍性和实用性。     

Estimating the structural credit risk model when equity prices are contaminated by trading noises

The transformed-data maximum likelihood estimation (MLE) method for structural credit risk models developed by Duan [Duan, J.-C., 1994. Maximum likelihood estimation using price data of the derivative contract. Mathematical Finance 4, 155–167] is extended to account for the fact that observed equity prices may have been contaminated by trading noises. With the presence of trading noises, the likelihood function based on the observed equity prices can only be evaluated via some nonlinear filtering scheme. We devise a particle filtering algorithm that is practical for conducting the MLE estimation of the structural credit risk model of Merton [Merton, R.C., 1974. On the pricing of corporate debt: The risk structure of interest rates. Journal of Finance 29, 449–470]. We implement the method on the Dow Jones 30 firms and on 100 randomly selected firms, and find that ignoring trading noises can lead to significantly over-estimating the firm’s asset volatility. The estimated magnitude of trading noise is in line with the direction that a firm’s liquidity will predict based on three common liquidity proxies. A simulation study is then conducted to ascertain the performance of the estimation method.