Construction of improved estimators of multinomial proportions

The improved large sample estimation theory for the probabilities of multi¬nomial distribution is developed under uncertain prior information (UPI) that the true proportion is a known quantity. Several estimators based on pretest and the Stein-type shrinkage rules are constructed. The expressions for the bias and risk of the proposed estimators are derived and compared with the maximum likelihood (ml) estimators. It is demonstrated that the shrinkage estimators are superior to the ml estimators. It is also shown that none of the preliminary test and shrinkage estimators dominate each other, though they perform y/ell relative to the ml estimators. The relative dominance picture of the estimators is presented. A simulation study is carried out to assess the performance of the estimators numerically in small samples.     

On parameter estimation in Bernoulli trials with dependence

A simple estimator is proposed for the dependence parameter for the Klotz model of Bernoulli trials with Markov dependence and it is compared with the ratio estimator given by Price and the approximate maximum likelihood estimator given by Klotz. The proposed estimator is shown to have considerably smaller bias than the other two estimators with comparable mean squared errors, and has all the large sample optimal properties that the other two estimators have.     

Old age and prosocial behavior: Social preferences or experimental confounds?

Experimental and field evidence indicate a positive link between social preferences and age, most strikingly between the elderly and young adults. However, it is possible that the seemingly positive link between age and preferences stems from confounds in experimental procedure. In a dictator game study we find that elderly participants do indeed transfer higher shares of their endowments to their peers than a standard sample of student participants. This result holds good even in treatments accounting for wealth differences and experimenter demand effects. However, we observe no difference in behavior when we compare elderly participants and students who have not previously participated in economic experiments. Accordingly, it is possible that the seemingly stronger social preferences of the elderly are due to confounds associated with lack of experience with economic experiments. In addition, when comparing incentivized and hypothetical transfer decisions, we observe a hypothetical bias in treatments with a “take” framing, but not in treatments with the standard “give” framing.     

Nonparametric estimation of copula functions for dependence modelling

Copulas characterize the dependence among components of random vectors. Unlike marginal and joint distributions, which are directly observable, the copula of a random vector is a hidden dependence structure that links the joint distribution with its margins. Choosing a parametric copula model is thus a nontrivial task but it can be facilitated by relying on a nonparametric estimator. Here the authors propose a kernel estimator of the copula that is mean square consistent everywhere on the support. They determine the bias and variance of this estimator. They also study the effects of kernel smoothing on copula estimation. They then propose a smoothing bandwidth selection rule based on the derived bias and variance. After confirming their theoretical findings through simulations, they use their kernel estimator to formulate a goodness-of-fit test for parametric copula models.     

An Australian map of British and Irish literacy in 1841

This contribution to the study of the literacy transition in Britain, Ireland, and Australia also touches on the relationship between literacy and international migration. Some 20,000 emigrants arrived in Australia in 1841 and their literacy is here established at the individual level, and then related to regional origins, occupations, religion, sex, and family status in the British Isles. The new Australian data offer unusual evidence to juxtapose with the prevailing account of British and Irish literacy. The paper makes systematic comparisons of the immigrant evidence with existing literacy findings for the populations of England and Wales, of Ireland, and the colonial population of Australia in the year 1841. The results also show extraordinary similarity of rank orderings between the Australian data and the conventional sources. The results show that the immigrants were consistently more literate than the home and the receiving populations and indicate a substantial link between migration and literacy.     

Rejoinder

Kaplan–Meier graphs of survival and other timed events are an extremely effective way to summarize outcome data from some types of clinical studies, but information on dates and the interaction among events is lost. A new mode for presenting such data is proposed, an Eventchart, that aids in looking at the study as a whole by simultaneously displaying the timing of 2–3 different types of events, including censoring and time-dependent covariate events. The chart helps to monitor accrual and can be used to “guesstimate” the amount of information resulting from additional enrollment and/or follow-up. Eventcharts are designed to supplement, not replace, quantitative methods of analysis or conventional survival graphs. Data from bone marrow transplantation and AIDS studies are used to illustrate the method. Terminology is suggested for describing the concepts and distinguishing among the complex of events studied in modern clinical trials, including timed events, loss and date censoring, and time-braided events.     

高师书法教学相关问题刍议

本文针对高师书法教学现状及存在问题,从目标定位、技法训练、审美趋同现象等几个方面对高师书法教学进行了探讨和思考。     

关于微格教学方式方法多样化的思考

微格教学作为一种师资培训方法,不但可以大面积、高效率地改善教师的课堂教学行为,而且对师范生将教学理论应用于教学有明显的意义。在微格教学中,教师若能在基本模式的基础上加以变化,灵活而具有创造性地运用多种教学方式、方法能形成生动、活泼、轻松、有趣的课堂气氛。在微格教学活动中追求教学方式、方法的多样化有利于培养学生的教学技能。     

Estimating Long and Short Run Effects in Static Panel Models

This paper assesses the biases of four different estimators with respect to the short run and the long run parameters if a static panel model is used, although the data generating process is a dynamic error components model. We analytically derive the associated biases and provide a discussion of the determinants thereof. Our analytical and numerical results as well as Monte Carlo simulations illustrate that the asymptotic bias of both the within and the between parameter with respect to the short run and long run impact can be substantial, depending on the memory of the data generating process, the length of the time series and the importance of the cross-sectional variation in the explanatory variables.     

Modelling reporting bias: the operative mortality rate for ruptured abdominal aortic aneurysm repair

Summary.  It is perhaps underappreciated that ruptured abdominal aortic aneurysm is a significant cause of mortality in the UK. The only curative treatment is an emergency operation and quantifying the success of this presents many difficulties. In particular, there is empirical evidence of reporting bias, suggesting that studies failing to report operating theatre mortality may be those where death in theatre is more common. We suggest a procedure for correcting for this bias and re-examine a recent meta-analysis of the available data. This casts considerable doubt on some conclusions from naïve analyses that do not take into account the potential bias. Perhaps most importantly, our procedure indicates a modest improvement in operating theatre mortality over the last 50 years, which is a trend that is not evident from the usual naïve analyses.