基于BP神经网络模型的宿州市人均生态足迹预测研究

利用人均生态足迹对宿州市生态形势进行评价,发现1997-2004年生态环境趋于恶化,经济快速发展过度消耗资源,并对环境造成一定程度危害,而2005～2007年生态环境趋于好转且态势平稳;并发现人均生态足迹的变化是宿州市生态安全形势的表征因子.在此基础上利用BP神经网络模型对宿州市1997-2005年生态足迹变化的影响因...     

顾客满意度研究及一种简捷测量方法：加权平均法

文章对顾客满意度研究的概念、内涵，研究流程进行了论述，并引用实例说明了用加权平均法计算顾客满意度指数(CSI)，可供理论工作者和实际工作者参考。     

On Average Predictive Comparisons and Interactions

In a regression context, consider the difference in expected outcome associated with a particular difference in one of the input variables. If the true regression relationship involves interactions, then this predictive comparison can depend on the values of the other input variables. Therefore, one may wish to consider an average predictive comparison as a target of inference, where the averaging is with respect to the population distribution of the input variables. We consider inferences about such targets, with emphasis on inferential performance when the regression model is misspecified. Particularly, in light of the difficulties in dealing with interaction terms in regression models, we examine inferences about average predictive comparisons when additive models are fitted to relationships truly involving pairwise interaction terms. We identify some circumstances where such inferences are consistent despite the model misspecification, notably when the input variables are independent, or have a multivariate normal distribution.     

基于最小二乘的职工收入统计分析

文章基于最小二乘法模型,利用2001-2007年相关统计数据,对我国职工工资水平指数、发展速度及发展趋势进行了分析,报告了我国职工收入水平状况现状;通过采用描述统计及回归分析方法,对2001-2007年分地区进行了我国职工收入调查,反映了我国职工收入存在的问题,取得我国职工平均收入存在地区差别的基本结论,即从总体上来说,我国就业职工的平均工资水平比较低,不同行业或者不同部门间就业人员的工资水平差距也比较大;给出提高职工平均收入、消除地区收入差别的建议及对策,即加快产业转型,实现跨越式发展,增加就业人数和就业质量,进一步夯实城乡居民增收的基础、打通地区间的资本等流通渠道,实现地区间资本、劳动力等资源顺利转移,增加经济欠发达地区的就业机会,提高该地区的人力资本,进一步深化企事业单位相关工资制度的改革,打破行业垄断,缩小不同行业间工资差距。     

一种实用的数字化算法

数字化仿形数控系统的核心部分是微型计算机硬件和软件。本文从平均曲率的概念出发,介绍在微型计算机上实现的一种数字化算法。     

Is increasing aircraft size common practice of airlines at congested airports?

If the overall demand for air transport grows, but additional airport capacity is not available at congested airports, we could assume that airlines will offer flights with more seats in order to cope with the demand. An analysis of frequency and average seat capacity developments at congested, and not yet congested airports, has shown that the hypothesis of bigger aircraft being used in congested situations is valid in most instances, although not at all airports. The objective of this paper is to report on an analysis of the development of average seat capacity at congested airports, in contrast to the situation at not yet congested airports, and to find out the reasons for airlines increasing the number of seats at congested airports, by means of a statistical model using variables including the degree of airport congestion and average flight distance.     

Treatment effect bounds: An application to Swan–Ganz catheterization

We reanalyze data from the observational study by Connors et al. (1996) on the impact of Swan–Ganz catheterization on mortality outcomes. The study by Connors et al. (1996) assumes that there are no unobserved differences between patients who are catheterized and patients who are not catheterized and finds that catheterization increases patient mortality. We instead allow for such differences between patients by implementing both the instrumental variable bounds of Manski (1990), which only exploits an instrumental variable, and the bounds of Shaikh and Vytlacil (2011), which exploit mild nonparametric, structural assumptions in addition to an instrumental variable. We propose and justify the use of indicators of weekday admission as an instrument for catheterization in this context. We find that in our application, the Manski (1990) bounds do not indicate whether catheterization increases or decreases mortality, where as the Shaikh and Vytlacil (2011) bounds reveal that at least for some diagnoses, Swan–Ganz catheterization reduces mortality at 7 days after catheterization. We show that the bounds of Shaikh and Vytlacil (2011) remain valid under even weaker assumptions than those described in Shaikh and Vytlacil (2011). We also extend the analysis to exploit a further nonparametric, structural assumption–that doctors catheterize individuals with systematically worse latent health–and find that this assumption further narrows these bounds and strengthens our conclusions. In our analysis, we construct confidence regions using the methodology developed in Romano and Shaikh (2008). We show in particular that the confidence regions are uniformly consistent in level over a large class of possible distributions for the observed data that include distributions where the instrument is arbitrarily “weak”.     

基于最小间隔法的重载运输通过能力研究

分析了平均间隔时间计算法的计算依据和步骤,列举出计算要素,结合现状行车量,计算重载运输通过能力。研究结果表明:最小平均间隔时间计算法的计算结果小于一般的铺画运行图的通过能力,并且较其他计算方法能更好地保证运行质量。     

基于人均寿命提高的养老金个人账户缴费率研究

现行的中国养老保险制度是"统筹账户和个人账户"相结合的部分积累模式。其中,个人账户不具备代际内收入再分配的功能,属于私人商品。个人账户缴费率的高低不仅影响到个人当期的可支配收入,而且间接影响到其退休后生活水平的高低。现行养老保险制度下的个人账户缴费率只能保障退休人员10年的生活,而目前男女退休职工的算术平均余命已接近17年,因此,随着人均寿命提高且不断延长,如果不能及时调整个人账户缴费率,那么退休人口将面临着因长寿带来的生活无保障的情况。本文则通过以现有的理论研究为基础进行合理测算,力求得出基于人均寿命提高调整个人账户缴费率的理论依据和政策依据。     

An np control chart for monitoring the mean of a variable based on an attribute inspection

This article proposes a new np control chart, called the np_x chart, that employs an attribute inspection (inspecting whether a unit is conforming or nonconforming) to monitor the mean value of a variable x. The distinctive feature of the np_x chart is using the statistical warning limits to replace the specification limits for the classification of conforming or nonconforming units. By optimizing the warning limits, the np_x chart usually outperforms the X¯ chart on the basis of same inspection cost. In addition, the np_x chart often works as a leading indicator of trouble and allows operators to take corrective action before any defective is actually produced.