港口吞吐量预测影响因素筛选方法研究

物流预测指标的筛选是物流需求预测工作的首要步骤。对港口吞吐量及其影响因素进行了分析,提出了预测指标的筛选原则和筛选方法,并以广西北部湾港口为例,利用2000—2008年的统计数据,采用灰色关联分析法和DPS数据处理软件工具求出各因素与港口吞吐量以及各因素之间的灰色关联度,最后根据筛选原则选出一组相关性强、结构合理的港口吞吐量预测指标。     

Ordinal equivalence of power notions in voting games

In this paper, we are concerned with the preorderings (SS) and (BC) induced in the set of players of a simple game by the Shapley–Shubik and the Banzhaf–Coleman's indices, respectively. Our main result is a generalization of Tomiyama's 1987 result on ordinal power equivalence in simple games; more precisely, we obtain a characterization of the simple games for which the (SS) and the (BC) preorderings coincide with the desirability preordering (T), a concept introduced by Isbell (1958), and recently reconsidered by Taylor (1995): this happens if and only if the game is swap robust, a concept introduced by Taylor and Zwicker (1993). Since any weighted majority game is swap robust, our result is therefore a generalization of Tomiyama's. Other results obtained in this paper say that the desirability relation keeps itself in all the veto-holder extensions of any simple game, and so does the (SS) preordering in all the veto-holder extensions of any swap robust simple game.     

Convergence criteria for interval-valued inequality indices

In this paper we introduce an interval-valued inequality index for random intervals based on a convex function. We show that if this function does not grow faster than x ^p , then the inequality index is continuous on the space of random intervals with finite p-th moment. A bound for the distance between the inequality indices of two random intervals is also constructed. An example is presented to motivate and illustrate the developments in this paper.     

A bivariate noncentral T-disttrtoution with applications

The particular bivariate noncentral t-distribution associated with two univariate noncentral t variates having a correlation coefficient of one is considered. Some applications and properties are presented together with tables in the same form as Johnson and Welch's tables for a univariate noncentral t-distribution.     

On the Sampling Distributions of the Estimated Process Loss Indices with Asymmetric Tolerances

The inverse Gaussian distribution provides a flexible model for analyzing positive, right-skewed data. The generalized variable test for equality of several inverse Gaussian means with unknown and arbitrary variances has satisfactory Type-I error rate when the number of samples (k) is small (Tian, 2006). However, the Type-I error rate tends to be inflated when k goes up. In this article, we propose a parametric bootstrap (PB) approach for this problem. Simulation results show that the proposed test performs very satisfactorily regardless of the number of samples and sample sizes. This method is illustrated by an example.