麦当劳套餐商品复合的效用最大化——以河北省某家麦当劳餐厅为例

随着物流和电子商务的发展,套餐类商品在经济活动中日趋广泛。论文针对麦当劳商品,将具有套餐类商品的商品复合问题进行了研究,探讨了商品复合、商品复合价值、商品复合效用和商品复合效用最大化等问题,分析了麦当劳快餐的商品复合问题,指出了麦当劳商品复合结构的特点决定了实现麦当劳商品复合效用最大化的简捷途径。通过对套餐价格节余对麦当劳商品消费最优化的影响分析,提出了一般套餐商品复合最优化问题的研究思路。套餐在现代服务业商品经济中具有重要影响,相应的研究适应了现实经济活动的特点,对探讨经济中的新现象和新问题具有一定的理论意义和应用价值。     

On the equivalence between descending bid auctions and first price sealed bid auctions

Bidding the same price in descending bid auctions and in first price sealed bid auctions is equivalent to expected utility maximizing behavior, and this is equivalent to dynamically consistent bidding. The claim that, in strategic form, descending bid and first price sealed bid auctions are the same game is thus shown to be false, since the mapping from strategies to payoffs is not the same for the two auction forms.     

A comparison of different procedures for principal component analysis in the presence of outliers

Principal component analysis (PCA) is a popular technique that is useful for dimensionality reduction but it is affected by the presence of outliers. The outlier sensitivity of classical PCA (CPCA) has caused the development of new approaches. Effects of using estimates obtained by expectation–maximization – EM and multiple imputation – MI instead of outliers were examined on the artificial and a real data set. Furthermore, robust PCA based on minimum covariance determinant (MCD), PCA based on estimates obtained by EM instead of outliers and PCA based on estimates obtained by MI instead of outliers were compared with the results of CPCA. In this study, we tried to show the effects of using estimates obtained by MI and EM instead of outliers, depending on the ratio of outliers in data set. Finally, when the ratio of outliers exceeds 20%, we suggest the use of estimates obtained by MI and EM instead of outliers as an alternative approach.     

Estimating the Relative Density of Snapper in and around a Marine Reserve Using a Log-Linear Mixed-Effects Model

Angling from small recreational fishing boats was used as a sampling method to quantify the relative density of snapper ( Pagrus auratus ) in six areas within the Cape Rodney-Okakari Point Marine Reserve (New Zealand) and four areas adjacent to the reserve. Penalized quasi-likelihood was used to fit a log-linear mixed-effects model having area and date as fixed effects and boat as a random effect. Simulation and first-order bias correction formulae were employed to assess the validity of the estimates of the area effects. The bias correction is known to be unsuitable for general use because it typically over-estimatesbias, and this was observed here. However, it was qualitatively useful for indicating the direction of bias and for indicating when estimators were approximately unbiased. The parameter of primary interest was the ratio of snapper density in the marine reserve versus snapper density outside the reserve, and the estimator of this parameter was first-order asymptotically unbiased. This ratio of snapper densities was estimated to be 11 (±3).     

成年子女外出状况及对农村家庭代际关系的影响

在我国大规模农村青壮年劳动力从乡到城转移的背景下,根据中国人民大学人口与发展研究中心2008年在河南、贵州部分农村进行的调查数据,从居住方式、代际互动、生活满意度几个方面对成年子女外出给农村家庭代际关系带来的影响进行分析。虽然农村留守老人在居住方式上出现了独居化、空巢化和隔代化的趋势,且在与外出子女间的代际资源交换中并未明显获益,但通过子女外出前后留守老人生活满意度的对比,发现留守老人的生活满意度显著提高。农村劳动力外出符合家庭利益最大化原则,同时提出相关政策建议。     

Simultaneous confidence bands for nonlinear regression models

The maximization and minimization procedure for constructing confidence bands about general regression models is explained. Then, using an existing confidence region about the parameters of a nonlinear regression model and the maximization and minimization procedure, a generally conservative simultaneous confidence band is constructed about the model. Two examples are given, and some problems with the procedure are discussed     

Optimal allocation of stratified samples with several variance constraints and equal workloads over time by geometric programming

We apply geometric programming, developed by Duffin, Peterson and Zener (1967), to the optimal allocation of stratified samples with several variance constraints arising from several estimates of deficiency rates in the quality control of administrative decisions. We develop also a method for imposing constraints on sample sizes to equalize workloads over time, as required by the practicalities of clerical work for quality control.

We allocate samples by an extension of the work of Neyman (1934), following the exposition of Cochran (1977). Davis and Schwartz (1987) developed methods for multiconstraint Neyman allocation by geometric programming for integrated sampling. They also applied geometric programming to Neyman allocation of a sample for estimating college enrollments by Cornell (1947) and Cochran (1977). This paper continues the application of geometric programming to Neyman allocation with multiple constraints on variances and workloads and minimpal sampling costs.     

智能电网实时电价社会福利最大化模型的研究

社会福利最大化模型及其推广、改进的模型是目前智能电网实时定价的有效方法之一。通过计算社会福利最大化模型的拉格朗日乘子,即影子价格,确定电力电价。本文对社会福利最大化中供电量下限(即最小发电量)在模型中的作用进行了研究,在一个符合通常实际情况的假设下,得到了去掉供电量下限的等价模型。所获得的模型减少了一个区间约束和一个变量。最后说明了简化的模型仍然适用于目前使用的在线对偶方法求解。     

The EM Algorithm—an Old Folk-song Sung to a Fast New Tune

Celebrating the 20th anniversary of the presentation of the paper by Dempster, Laird and Rubin which popularized the EM algorithm, we investigate, after a brief historical account, strategies that aim to make the EM algorithm converge faster while maintaining its simplicity and stability (e.g. automatic monotone convergence in likelihood). First we introduce the idea of a 'working parameter' to facilitate the search for efficient data augmentation schemes and thus fast EM implementations. Second, summarizing various recent extensions of the EM algorithm, we formulate a general alternating expectation–conditional maximization algorithm AECM that couples flexible data augmentation schemes with model reduction schemes to achieve efficient computations. We illustrate these methods using multivariate t -models with known or unknown degrees of freedom and Poisson models for image reconstruction. We show, through both empirical and theoretical evidence, the potential for a dramatic reduction in computational time with little increase in human effort. We also discuss the intrinsic connection between EM-type algorithms and the Gibbs sampler, and the possibility of using the techniques presented here to speed up the latter. The main conclusion of the paper is that, with the help of statistical considerations, it is possible to construct algorithms that are simple, stable and fast.     

企业财务目标探析

企业财务目标一直是国内外财务学者关注的焦点之一。随着我国国有企业改革的进一步深化 ,现代企业制度的逐步建立与完善 ,直接反映着理财环境变化的财务管理目标 ,应根据环境的变化做适当调整。过去关于企业财务目标的几个重要表述各有其优缺点。分析比较与研究表明 ,企业价值最大化应是我国目前企业财务目标的理性选择