Bayesian MCMC Mapping of Quantitative Trait Loci in a Half-sib Design: a Graphical Model Perspective

Graphical models provide a powerful and flexible approach to the analysis of complex problems in genetics. While task-specific software may be extremely efficient for any particular analysis, it is often difficult to adapt to new computational challenges. By viewing these genetic applications in a more general framework, many problems can be handled by essentially the same software. This is advantageous in an area where fast methodological development is essential. Once a method has been fully developed and tested, problem-specific software may then be required. The aim of this paper is to illustrate the potential use of a graphical model approach to genetic analyses by taking a very simple and well-understood problem by way of example.     

Aggregate volatility expectations and threshold CAPM

We propose a volatility-based capital asset pricing model (V-CAPM) in which asset betas change discretely with respect to changes in investors’ expectations regarding near-term aggregate volatility. Using a novel measure to proxy uncertainty about expected changes in aggregate volatility, i.e. monthly range of the VIX index (RVIX), we find that portfolio betas change significantly when uncertainty about aggregate volatility expectations is beyond a certain threshold level. Due to changes in their market betas, small and value stocks are perceived as riskier than their big and growth counterparts in bad times, when uncertainty about aggregate volatility expectations is high. The proposed model yields a positive and significant market risk premium during periods when investors do not expect significant uncertainty in near-term aggregate volatility. Our findings support a volatility-based time-varying risk explanation.     

Conditioning as disintegration

Conditional probability distributions seem to have a bad reputation when it comes to rigorous treatment of conditioning. Technical arguments are published as manipulations of Radon–Nikodym derivatives, although we all secretly perform heuristic calculations using elementary definitions of conditional probabilities. In print, measurability and averaging properties substitute for intuitive ideas about random variables behaving like constants given particular conditioning information.
One way to engage in rigorous, guilt-free manipulation of conditional distributions is to treat them as disintegrating measures—families of probability measures concentrating on the level sets of a conditioning statistic. In this paper we present a little theory and a range of examples—from EM algorithms and the Neyman factorization, through Bayes theory and marginalization paradoxes—to suggest that disintegrations have both intuitive appeal and the rigor needed for many problems in mathematical statistics.     

出口退税、汇率调整与出口企业的最优销量——基于相互市场古诺模型的分析

文章利用冰山假说把国内税率、出口退税率以及汇率政策因素纳入存在多个国内与外国企业的相互市场古诺模型,分析了以国内税、出口退税与汇率为核心的策略性贸易政策对出口企业利润最大化的最优出口销量与国内销售的影响,并且以这种比较静态分析为基础,对各种单一政策与多项政策组合的调整效力进行排序。这些分析得出如下的结论:就单一政策的调整效力而言,出口退税优于国内税收与汇率政策;就政策组合的调整效力而言,出口退税与国内税组合优于国内税与汇率的组合。     

Conditional ordering extensions

We produce a solution to the problem of extending a quasiordering conditional on a finite list of ex-ante comparisons between pairs. This constitutes yet another extension of the classical Szpilrajn’s theorem. Some examples of use of our result follow.     

Inference on endogenously censored regression models using conditional moment inequalities

Under a quantile restriction, randomly censored regression models can be written in terms of conditional moment inequalities. We study the identified features of these moment inequalities with respect to the regression parameters where we allow for covariate dependent censoring, endogenous censoring and endogenous regressors. These inequalities restrict the parameters to a set. We show regular point identification can be achieved under a set of interpretable sufficient conditions. We then provide a simple way to convert conditional moment inequalities into unconditional ones while preserving the informational content. Our method obviates the need for nonparametric estimation, which would require the selection of smoothing parameters and trimming procedures. Without the point identification conditions, our objective function can be used to do inference on the partially identified parameter. Maintaining the point identification conditions, we propose a quantile minimum distance estimator which converges at the parametric rate to the parameter vector of interest, and has an asymptotically normal distribution. A small scale simulation study and an application using drug relapse data demonstrate satisfactory finite sample performance.     

对会员卡法律关系性质的探究

会员卡源于西方会员制,在高档场所实行,体现身份和地位。根据不同标准,中国会员卡有准入式与非准入式、预付式与非预付式之分类。会员卡与信用卡、公交IC卡不能等同。准入式与预付式会员卡法律关系是继续性合同。准入式下的持卡人既是会员也是成员,其身份具有双重性;而非预付式会员卡法律关系构成两个相互关联且具有一定独立性的联立合同。     

中国出口退税政策制度演化的经济效应分析

自1994年税制改革至今,中国出口退税制度发生了一系列的制度变迁。而出口退税制度的演变过程对中国的贸易进出口乃至中国经济产生了较明显的影响。本文在前人研究的基础上,重点从外贸出口、政府财政及企业三大方面进行分析,指出中国现行的出口退税制度的调整在整体经济运行的不同层面上发挥的效用之显著;并对今后该制度的改革提出相应的建议,以期对本国对外贸易的发展有所借鉴和启发。