Likelihood ratio test for discordancy with slippage alternatives

A likelihood ratio test for discordancy in the sample is considered with slippage alternatives. It is shown for a wide class of univariate distributions that only the extreme observations in the sample need to be tested for discordancy. This result provides a firmer support to many commonly used discordancy tests that take only extreme observations as candidates. The problem of testing multiple discordant observations is also discussed.     

How many ways can you look at a proportion?: cross-community vote transfers in Northern Ireland after the Belfast Agreement

Summary.  The single transferable vote is a method of election that allows voters to mark candidates in order of preference. Votes that are not required to elect a candidate are passed to the next candidate in the voter's order of preference. Results of this kind of election give us data about the degree to which voters of a given persuasion are willing to pass their vote to a candidate of a different persuasion. Measures of voters' willingness to pass a vote to a candidate of a different persuasion are of particular interest in places such as Northern Ireland, where communities differ by religion and national aspiration, and agreed new political institutions are based on cross-community power-sharing. How we quantify this voting data may depend on the questions that we want to answer, of course. But, to understand changes in how the voter orders her or his preference, one may need to ask several questions, and to quantify the results of the election in more than one way.     

Shape constrained kernel density estimation

In this paper, a method for estimating monotone, convex and log-concave densities is proposed. The estimation procedure consists of an unconstrained kernel estimator which is modified in a second step with respect to the desired shape constraint by using monotone rearrangements. It is shown that the resulting estimate is a density itself and shares the asymptotic properties of the unconstrained estimate. A short simulation study shows the finite sample behavior.     

Power-law scaling behavior analysis of financial time series model by voter interacting dynamic system

We investigate the power-law scaling behaviors of returns for a financial price process which is developed by the voter interacting dynamic system in comparison with the real financial market index (Shanghai Composite Index). The voter system is a continuous time Markov process, which originally represents a voter's attitude on a particular topic, that is, voters reconsider their opinions at times distributed according to independent exponential random variables. In this paper, the detrended fluctuation analysis method is employed to explore the long range power-law correlations of return time series for different values of parameters in the financial model. The findings show no indication or very weak long-range power-law correlations for the simulated returns but strong long-range dependence for the absolute returns. The multiplier distribution is studied to demonstrate directly the existence of scale invariance in the actual data of the Shanghai Stock Exchange and the simulation data of the model by comparison. Moreover, the Zipf analysis is applied to investigate the statistical behaviors of frequency functions and the distributions of the returns. By a comparative study, the simulation data for our constructed price model exhibits very similar behaviors to the real stock index, this indicates somewhat rationality of our model to the market application.     

Structure identification and variable selection in geographically weighted regression models

Geographically weighted regression (GWR) is an important tool for exploring spatial non-stationarity of a regression relationship, in which whether a regression coefficient really varies over space is especially important in drawing valid conclusions on the spatial variation characteristics of the regression relationship. This paper proposes a so-called GWGlasso method for structure identification and variable selection in GWR models. This method penalizes the loss function of the local-linear estimation of the GWR model by the coefficients and their partial derivatives in the way of the adaptive group lasso and can simultaneously identify spatially varying coefficients, nonzero constant coefficients and zero coefficients. Simulation experiments are further conducted to assess the performance of the proposed method and the Dublin voter turnout data set is analysed to demonstrate its application.     

Estimation of Several Intraclass Correlation Coefficients

An intraclass correlation coefficient observed in several populations is estimated. The basis is a variance-stabilizing transformation. It is shown that the intraclass correlation coefficient from any elliptical distribution should be transformed in the same way. Four estimators are compared. An estimator where the components in a vector consisting of the transformed intraclass correlation coefficients are estimated separately, an estimator based on a weighted average of these components, a pretest estimator where the equality of the components is tested and then the outcome of the test is used in the estimation procedure, and a James-Stein estimator which shrinks toward the mean.     

Coefficient of variation for the L-class of life distributions

It is shown that the coefficient of variation for the L-class of life distributions is less than or equal to 1.We prove that a d.f. F, belonging to the L-class of life distributions , is exponential if and only if its coefficient of variation is equal to 1.     

Some asymptotic behaviour of the bootstrap estimates on a finite sample

Bootstrapping the mean, variance, standard error of the mean, regression coefficient and its standard error is considered. It is shown that at a fixed sample size bootstrap estimates converge to classical sample estimates as the number of bootstrap replications tends to infinity. For the mean, variance and regression coefficient, convergence almost everywhere is proven; for the standard error of the mean and standard error of the regression coefficient, weak convergence is proven. The speed of convergence is illustrated by simulation results.     

A simple derivation of the distribution of the multiple correlation coefficient

It is shown that the non-null distribution of the multiple correlation coefficient may be derived rather easily if the correlated normal variables are defined in a convenient vay. The invariance of the correlation distribution to linear transformations of the variables makes the results generally applicable. The distribution is derived as the well-known mixture of null distributions, and some generalizations when the variables are not normally distributed are indicated.     

Nash equilibria for voter models with randomly perceived positions

We introduce a voter model in which parties’ intended policy positions are perceived by voters with some random uncertainty. We prove that for a total of three parties, under some mild assumptions, this model has a Nash equilibrium in which all three parties attempt to contest the election with the median policy. This contrasts with Duverger’s Law, which asserts that only two parties will contest the election at all, consistent with some different voter models.     

Improved confidence intervals for the exponential mean via tail functions

Abstract

The method of tail functions is applied to confidence estimation of the exponential mean in the presence of prior information. It is shown how the “ordinary” confidence interval can be generalized using a class of tail functions and then engineered for optimality, in the sense of minimizing prior expected length over that class, whilst preserving frequentist coverage. It is also shown how to derive the globally optimal interval, and how to improve on this using tail functions when criteria other than length are taken into consideration. Probabilities of false coverage are reported for some of the intervals under study, and the theory is illustrated by application to confidence estimation of a reliability coefficient based on some survival data.     

Location and Scale Estimation with Correlation Coefficients

This article shows how to use any correlation coefficient to produce an estimate of location and scale. It is part of a broader system, called a correlation estimation system (CES), that uses correlation coefficients as the starting point for estimations. The method is illustrated using the well-known normal distribution. This article shows that any correlation coefficient can be used to fit a simple linear regression line to bivariate data and then the slope and intercept are estimates of standard deviation and location. Because a robust correlation will produce robust estimates, this CES can be recommended as a tool for everyday data analysis. Simulations indicate that the median with this method using a robust correlation coefficient appears to be nearly as efficient as the mean with good data and much better if there are a few errant data points. Hypothesis testing and confidence intervals are discussed for the scale parameter; both normal and Cauchy distributions are covered.     

Distribution-free subset selection for incompletely ranked data

In market research and some other areas, it is common that a sample of n judges (consumers, evaluators, etc.) are asked to independently rank a series of k objects or candidates. It is usually difficult to obtain the judges' full cooperation to completely rank all k objects. A practical way to overcome this difficulty is to give each judge the freedom to choose the number of top candidates he is willing to rank. A frequently encountered question in this type of survey is how to select the best object or candidate from the incompletely ranked data. This paper proposes a subset selection procedure which constructs a random subset of all the k objects involved in the survey such that the best object is included in the subset with a prespecified confidence. It is shown that the proposed subset selection procedure is distribution-free over a very broad class of underlying distributions. An example from a market research study is used to illustrate the proposed procedure.     

Estimators of the multiple correlation coefficient: Local robustness and confidence intervals

Many robust regression estimators are defined by minimizing a measure of spread of the residuals. An accompanying R ²-measure, or multiple correlation coefficient, is then easily obtained. In this paper, local robustness properties of these robust R ²-coefficients are investigated. It is also shown how confidence intervals for the population multiple correlation coefficient can be constructed in the case of multivariate normality.     

A sufficient condition for the MSE dominance of the positive-part shrinkage estimator when each individual regression coefficient is estimated in a misspecified linear regression model

In this paper, assuming that there exist omitted explanatory variables in the specified model, we derive the exact formula for the mean squared error (MSE) of a general family of shrinkage estimators for each individual regression coefficient. It is shown analytically that when our concern is to estimate each individual regression coefficient, the positive-part shrinkage estimators have smaller MSE than the original shrinkage estimators under some conditions even when the relevant regressors are omitted. Also, by numerical evaluations, we showed the effects of our theorem for several specific cases. It is shown that the positive-part shrinkage estimators have smaller MSE than the original shrinkage estimators for wide region of parameter space even when there exist omitted variables in the specified model.     

Tail dependence of skew t-copulas

We examine tail behavior of skew t-copula in the bivariate case. The tail dependence coefficient is calculated for different skewing parameter values and compared with the corresponding coefficient for the t-copula. It is shown that depending on skewing parameter values, the tail dependence coefficient can differ considerably from the tail dependence of the t-copula. The speed of convergence of the estimator of tail dependence coefficient to its theoretical value is examined in a simulation experiment. Method of moments and maximum likelihood method are compared by simulation either. In the considered cases, maximum likelihood method converged faster to the theoretical value.     

Combining census,dual-system,and evaluation study data to estimate population shares

"The 1990 [U.S.] census and Post-Enumeration Survey produced census and dual system estimates (DSE) of population by domain, together with an estimated sampling covariance matrix of the DSE. Estimates of the bias of the DSE were derived from various PES evaluation programs. Of the three sources, the unadjusted census is the least variable but is believed to be the most biased, the DSE is less biased but more variable, and the bias estimates may be regarded as unbiased but are the most variable. This article addresses methods for combining the census, the DSE, and bias estimates obtained from the evaluation programs to produce accurate estimates of population shares, as measured by weighted squared- or absolute-error loss functions applied to estimated population shares of domains."     

参股银行、终极控制人与公司投资行为

研究上市公司参股银行对不同终极控制人的公司投资行为的影响,以揭示在股东—债权人代理冲突下,不同终极控制人的上市公司参股银行后在银行对其不同的外在约束下所产生的对公司投资行为的不同影响,并基于中国沪深股市2009—2012年间150家参股银行的公司共600个观测值的平衡面板数据进行了实证研究,研究结果表明:随着公司持股银行的比例增加,对银行业金融资源的控制能力增强,可以抑制公司的过度投资和投资不足行为,投资扭曲减少;终极控制权为中央或者地方政府的上市公司参股银行之后面临银行的软约束使其过度投资或投资不足现象更严重,而非中央或者地方政府的上市公司参股银行后其投资行为受到银行的硬约束,则可以有效抑制其过度投资和投资不足。研究结论为上市公司低效率投资现象提供了一种解释,同时也为监管部门设计约束政府干预公司经营行为的机制提供了一定的经验依据。     

Penalized optimal designs for dose-finding

Optimal design under a cost constraint is considered, with a scalar coefficient setting the compromise between information and cost. It is shown that for suitable cost functions, by increasing the value of the coefficient one can force the support points of an optimal design measure to concentrate around points of minimum cost. An example of adaptive design in a dose-finding problem with a bivariate binary model is presented, showing the effectiveness of the approach.     

On the use of the Stein variance estimator in the double <Emphasis Type="Italic">k</Emphasis>-class estimator when each individual regression coefficient is estimated

In this paper we consider the double k-class estimator which incorporates the Stein variance estimator. This estimator is called the SVKK estimator. We derive the explicit formula for the mean squared error (MSE) of the SVKK estimator for each individual regression coefficient. It is shown analytically that the MSE performance of the Stein-rule estimator for each individual regression coefficient can be improved by utilizing the Stein variance estimator. Also, MSE’s of several estimators included in a family of the SVKK estimators are compared by numerical evaluations.