Combining the t test and Wilcoxon's rank-sum test

In the two-sample location-shift problem, Student's t test or Wilcoxon's rank-sum test are commonly applied. The latter test can be more powerful for non-normal data. Here, we propose to combine the two tests within a maximum test. We show that the constructed maximum test controls the type I error rate and has good power characteristics for a variety of distributions; its power is close to that of the more powerful of the two tests. Thus, irrespective of the distribution, the maximum test stabilizes the power. To carry out the maximum test is a more powerful strategy than selecting one of the single tests. The proposed test is applied to data of a clinical trial.     

Statistical Inference on a Stochastic Epidemic Model

In this work, we develop statistical inference for the parameters of a discrete-time stochastic SIR epidemic model. We use a Markov chain for describing the dynamic behavior of the epidemic. Specifically, we propose estimators for the contact and removal rates based on the maximum likelihood and martingale methods, and establish their asymptotic distributions. The obtained results are applied in the statistical analysis of the basic reproduction number, a quantity that is useful in establishing vaccination policies. In order to evaluate the population size for which the results are useful, a numerical study is carried out. Finally, a comparison of the maximum likelihood and martingale estimators is conducted by means of Monte Carlo simulations.     

试析科学发展观的实践价值

科学发展观不仅仅是一个学理性的命题,更重要的是它进一步回答了在中国特色社会主义伟大事业中＂实现什么样的发展和怎样发展＂这一具有极强针对性和可操作性的重大实践命题,它的实践价值表现为：科学发展观与新世纪新阶段的时代主题相契合、与我国经济社会发展存在的突出问题相对接,具有鲜明的时代性;科学发展观是全面建设小康社会和构建社会主义和谐社会的根本指针,具有重大的指导性;科学发展观引导领导干部树立正确的政绩观和群众观,具有极强的规正性。     

A QUASI‐LOCALLY MOST POWERFUL TEST FOR CORRELATION IN THE CONDITIONAL VARIANCE OF POSITIVE DATA

A test is derived for short‐memory correlation in the conditional variance of strictly positive, skewed data. The test is quasi‐locally most powerful (QLMP) under the assumption of conditionally gamma data. Analytical asymptotic relative efficiency calculations show that an alternative test, based on the first‐order autocorrelation coefficient of the squared data, has negligible relative power to detect correlation in the conditional variance. Finite‐sample simulation results confirm the poor performance of the squares‐based test for fixed alternatives, as well as demonstrating the poor performance of the test based on the first‐order autocorrelation coefficient of the raw (levels) data. The robustness of the QLMP test, both to misspecification of the conditional distribution and to misspecification of the dynamics, is also demonstrated using simulation. The test is illustrated using financial trade durations data.     

Conditional quantile estimation with auxiliary information for left-truncated and dependent data

In this paper, the empirical likelihood method is used to define a new estimator of conditional quantile in the presence of auxiliary information for the left-truncation model. The asymptotic normality of the estimator is established when the data exhibit some kind of dependence. It is assumed that the lifetime observations with multivariate covariates form a stationary α‐mixing sequence. The result shows that the asymptotic variance of the proposed estimator is not larger than that of standard kernel estimator. Finite sample behavior of the estimator is investigated via simulations too.     

Efficiency of Large Private Value Auctions

We consider discriminatory and uniform price auctions for multiple identical units of a good. Players have private values, possibly asymmetrically distributed and for multiple units. Our setting allows for aggregate uncertainty about demand and supply. In this setting, equlibria generally will be inefficient. Despite this, we show that such auctions become arbitrarily close to efficient if they are “large,” and use this to derive an asymptotic characterization of revenue and bidding behavior.     

Mediating self‐hood: exploring the construction and maintenance of identity by mothers of children labeled with autism spectrum disorder

Based on the findings of a qualitative study, this article describes how mothers of children labeled with autism spectrum disorder (ASD) mediate for their children in interactions with those who are unfamiliar with ASD. Data were collected through in‐depth interviews and participant observations. Findings indicate that mothers mediate for their children because they perceive hostility and lack of accommodation for their children on the part of unfamiliars. As they mediate, mothers attempt to construct and maintain positive identities for their children by explaining and reframing their children’s behaviors to influence the interpretations and responses of unfamiliars. I argue that in these interactions mothers function as proxy selves for their children because they are attempting to influence the perceptions others develop of their children, thus shaping their children’s social identity in the process. The findings of this study demonstrate the active, interpretive role that many mothers of children with autism play as they continually sort and assess information in order to determine what is in the best interests of their children. Further, the findings presented here demonstrate the social nature of self‐hood and identity, that all people involve others in the performance of their self‐hood. In this way and others, people labeled with ASD have much in common with those considered normal.     

集权制度文化的观念形态及其价值论

集权制度文化在制度变迁后以观念形态传承下来,至今有深远影响。在社会主义政治文化建设中,既要剔除集权制度文化的消极成分,同时要注重开发利用其整体为上理念、统筹兼顾功能和公平效率优势等现代价值。     

差分方程x_(n+1)=(ax_(n-1))/(1+bx_nx_(n-1))的全局稳定性

研究了差分方程x_(n+1)=ax_(n-1)/1+bx_nx_(n-1),n=0,1,2,…(a,b,x-1,x0为非负实数)的全局性质,得到了方程所有正解的单调性、有界性、周期性、局部渐近稳定性和全局渐近稳定性等相关结果.     

Tests for Unit Roots and the Initial Condition

The paper analyzes the impact of the initial condition on the problem of testing for unit roots. To this end, we derive a family of optimal tests that maximize a weighted average power criterion with respect to the initial condition. We then investigate the relationship of this optimal family to popular tests. We find that many unit root tests are closely related to specific members of the optimal family, but the corresponding members employ very different weightings for the initial condition. The popular Dickey‐Fuller tests, for instance, put a large weight on extreme deviations of the initial observation from the deterministic component, whereas other popular tests put more weight on moderate deviations. Since the power of unit root tests varies dramatically with the initial condition, this paper explains the results of comparative power studies of unit root tests. The results allow a much deeper understanding of the merits of particular tests in specific circumstances, and a guide to choosing which statistics to use in practice.