Testing Covariance Stationarity

In this paper, we show that the widely used stationarity tests such as the Kwiatkowski Phillips, Schmidt, and Shin (KPSS) test have power close to size in the presence of time-varying unconditional variance. We propose a new test as a complement of the existing tests. Monte Carlo experiments show that the proposed test possesses the following characteristics: (i) in the presence of unit root or a structural change in the mean, the proposed test is as powerful as the KPSS and other tests; (ii) in the presence of a changing variance, the traditional tests perform badly whereas the proposed test has high power comparing to the existing tests; (iii) the proposed test has the same size as traditional stationarity tests under the null hypothesis of stationarity. An application to daily observations of return on U.S. Dollar/Euro exchange rate reveals the existence of instability in the unconditional variance when the entire sample is considered, but stability is found in subsamples.     

Nonparametric Entropy-Based Tests of Independence Between Stochastic Processes

This article develops nonparametric tests of independence between two stochastic processes satisfying β-mixing conditions. The testing strategy boils down to gauging the closeness between the joint and the product of the marginal stationary densities. For that purpose, we take advantage of a generalized entropic measure so as to build a whole family of nonparametric tests of independence. We derive asymptotic normality and local power using the functional delta method for kernels. As a corollary, we also develop a class of entropy-based tests for serial independence. The latter are nuisance parameter free, and hence also qualify for dynamic misspecification analyses. We then investigate the finite-sample properties of our serial independence tests through Monte Carlo simulations. They perform quite well, entailing more power against some nonlinear AR alternatives than two popular nonparametric serial-independence tests.     

Bayesian prediction of waiting times in stochastic models

The authors show how saddlepoint techniques lead to highly accurate approximations for Bayesian predictive densities and cumulative distribution functions in stochastic model settings where the prior is tractable, but not necessarily the likelihood or the predictand distribution. They consider more specifically models involving predictions associated with waiting times for semi‐Markov processes whose distributions are indexed by an unknown parameter θ. Bayesian prediction for such processes when they are not stationary is also addressed and the inverse‐Gaussian based saddlepoint approximation of Wood, Booth & Butler (1993) is shown to accurately deal with the nonstationarity whereas the normal‐based Lugannani & Rice (1980) approximation cannot, Their methods are illustrated by predicting various waiting times associated with M/M/q and M/G/1 queues. They also discuss modifications to the matrix renewal theory needed for computing the moment generating functions that are used in the saddlepoint methods.     

Optimal design of clinical trials comparing several treatments with a control

Clinical trials are often designed to compare several treatments with a common control arm in pairwise fashion. In this paper we study optimal designs for such studies, based on minimizing the total number of patients required to achieve a given level of power. A common approach when designing studies to compare several treatments with a control is to achieve the desired power for each individual pairwise treatment comparison. However, it is often more appropriate to characterize power in terms of the family of null hypotheses being tested, and to control the probability of rejecting all, or alternatively any, of these individual hypotheses. While all approaches lead to unbalanced designs with more patients allocated to the control arm, it is found that the optimal design and required number of patients can vary substantially depending on the chosen characterization of power. The methods make allowance for both continuous and binary outcomes and are illustrated with reference to two clinical trials, one involving multiple doses compared to placebo and the other involving combination therapy compared to mono-therapies. In one example a 55% reduction in sample size is achieved through an optimal design combined with the appropriate characterization of power.     

Some theory and practical uses of trimmed L-moments

Trimmed L-moments, defined by Elamir and Seheult [2003. Trimmed L-moments. Comput. Statist. Data Anal. 43, 299–314], summarize the shape of probability distributions or data samples in a way that remains viable for heavy-tailed distributions, even those for which the mean may not exist. We derive some further theoretical results concerning trimmed L-moments: a relation with the expansion of the quantile function as a weighted sum of Jacobi polynomials; the bounds that must be satisfied by trimmed L-moments; recurrences between trimmed L-moments with different degrees of trimming; and the asymptotic distributions of sample estimators of trimmed L-moments. We also give examples of how trimmed L-moments can be used, analogously to L-moments, in the analysis of heavy-tailed data. Examples include identification of distributions using a trimmed L-moment ratio diagram, shape parameter estimation for the generalized Pareto distribution, and fitting generalized Pareto distributions to a heavy-tailed data sample of computer network traffic.     

“联系说”视角下商标俗称抢注案的法律思考

商标权的客体为相关公众所认知的商标与商标所标识的商品或服务之间的联系,以此为基础可以认定商标俗称的抢注构成对商标权的侵犯,同时,商标俗称可以被认定为近似商标的一种形式,从而适用《商标法》第52条的规定。此外,在商标俗称的问题上,不能适用法律对驰名商标的特殊保护。     

深圳十年规划建设理论与实践初探

本文根据深圳十年规划与建设经验,对市场经济条件下的城市规划理论、乡镇城市化、开放型城市的交通与电讯网络、城市生态环境的保护、投资软硬环境的建设,以及如何提高城市规划的科学水平等问题作了探讨。     

Path(ological) Dependency? Core Competencies from an Organizational Perspective

The development of the 'resource-based theory of the firm' has helped to reorient the field of strategic management towards a focus on the organizational processes and structures which produce 'core competencies'. By challenging previous assumptions of market determinism this approach seems to open up the prospect of a greater dialogue with the theories and concerns of organization studies. This paper aims to determine the scope of such a dialogue by developing an appreciation and critique of the core competencies framework from an organizational perspective. In this context, the key feature of resource-based theories is seen to be their focus on organizational knowledge rather than decision-making processes as the engine of competitive performance. This focus has a powerful resonance with studies of knowledge in organizations, particularly those forms of knowledge which are linked to product and process design.
However, despite the important shift towards a knowledge-based view of competition, the core competencies approach fails to follow the logic of its own argument as far as the organizational appropriation of knowledge is concerned. In their pursuit of an ontological model of competitive performance –defining the essential causes of firm competitiveness – resource-based approaches neglect the socially embedded qualities of organizational knowledge. As a result, the social construction of knowledge, encompassing the dilemmas posed by the employment relationship and the pitfalls of institutionalization, is neglected. Instead, a smoothly linear model is developed linking skills, competence and competitiveness. This mechanistic view is further reinforced by reliance on a command and control model of the management process. Organizational knowledge is not a biddable resource at the disposal of top management.     

西方公共治理理论体系的构建及对我国的启示

西方公共治理的五大前沿理论有共性也有差异,这种差异性并非是对立之存在,而是互补之存在。新公共服务理论在理念层面上,突出服务理念;网络（化）治理理论在治理结构方面,强调网络结构;整体性治理理论在治理方式方面,提倡整合或合作的治理方式;数字治理理论在治理工具方面,主张大数据技术或智能化治理;公共价值管理理论在治理目标或使命方面,认为创造公共价值将是未来的方向。因此,我们应将治理的理念、结构、方式、工具、使命等层面的优势整合起来,构建西方公共治理理论体系,发挥出整体优势,理论群优势。这一理论体系的构建既能反观我国当前的治理背景、设计出合理的治理方案,又能在理念、结构、机制、工具、目标层面启发我国国家治理体系构建。