An investigation of transformation-based prediction interval for the Weibull median life

Statistical inference based on the Weibull distribution, a distribution widely used in reliability and survival analysis, is usually difficult as it often involves numerical computation and approximation. However, this distribution can be transformed to near-normality by a simple power transformation. Based on this transformation, a prediction interval (PI) for its median can be easily constructed through an inverse transformation. The procedure for selecting the best power transformation through minimizing Kullback-Leibler information is described. The property of this transformation-based PI is investigated. Simple correction factors are also proposed. It is shown that the transformation-based PI with corrections performs well, irrespective of the sample size and parameter values. Simulation results show that the new PI generally outperforms the existing PI. Numerical examples are given for illustration.     

交叉中值模型在物流设施选址中的应用研究

城镇化目前已经成为扩大改革开放的一项重要举措,但随着而来的就是相关基础服务设施不完善,严重影响了新城镇广大居民的生活质量和水平。因此,对于新建城镇相关物流服务设施的选址问题就变得尤为重要,交叉中值模型则是一个城镇区域内单一设施连续点选址的非常适合的方法。     

一种基于LSB的改进信息隐藏算法及实现

传统的LSB算法是将私密信息以二进制的形式嵌入到载体像素值的最低有效位,这样对图像的质量负面影响可以降到最小。本文提出了一种将过滤技术与LSB算法相结合的信息隐藏算法。利用过滤技术增强图片质量,利用LSB算法进行私密信息的嵌入。改进型的LSB算法比原算法具有更高信息存储量以及更高信息安全性等优点。     

An empirical investigation into the gravitation and convergence of industry return rates in OECD countries

Tests are offered for the hypotheses that sectoral average profit rates and incremental return rates are gravitating around or converging towards a common value. We study data for various OECD countries relying on an econometric method able to account for residual autocorrelation and cross‐sector correlation. Our null hypotheses receive only a mixed empirical support. This is interpreted as the result of various kinds of limitations to capital mobility. Policy implications are discussed.     

经济人口重心的动态转移与区域经济发展

改革开放以来到20世纪90年代初,我国经济重心的主要变动方向由北向南,区域经济差距的矛盾主要体现为南北矛盾.90年代中期以后,南北差距逐渐缩小,而东西差距有所扩大,区域经济差距的矛盾由南北转向东西,人口重心主要在南北方向上不均衡.由于地区经济发展水平的差异是导致人口迁移的主要因素,人口重心滞后于经济重心的变化,人口迁移的流向是影响人口重心迁移的重要因素.有计划地促进沿海和内陆地区间较均衡的经济发展,将有利于实现人口迁移与经济的协调发展.     

An Anatomy Of Racial and Ethnic Trends in Male Earnings in the U.S

Progress in narrowing black–white earnings differences has been far from continuous, with some of the apparent progress resulting from labor force withdrawal among lower‐skilled African Americans. This paper documents racial and ethnic differences in male earnings from 1950 through 2010 using data from the decennial census and American Community Surveys. Emphasis is given to annual rather than weekly or hourly earnings. We take a quantile approach, providing evidence on medians and other percentiles of the distribution. Treatment of imputed earnings greatly affects measured outcomes. Hispanic men have exhibited earnings growth similar to white men over several decades. Black men have been left behind economically due in large part to increased joblessness, a process exacerbated by weak labor market conditions. By 2010, joblessness had risen to over 40 percent and the median black–white earnings gap was the largest in at least 60 years.     

Bounds for the difference between median and mean of beta and negative binomial distributions

Summary We obtain bounds for the difference between the median and mean of the beta and negative binomial distributions using elementary methods.     

基于邻域信息的噪声图像的恢复

噪声图像的恢复是影响图像信息提取的一个重要因素。主要针对现存的噪声图像恢复算法在消除细线及椒盐噪声方面的困难,基于待检像素的邻域信息提出了一种针对细线和椒盐噪声感染的图像的恢复算法。实验结果表明,文中所提算法不仅具有很好的抑制细线及椒盐噪声的效果,而且有效地保存了图像的细节与结构信息,同时对其它的噪声也有一定的抑制作用。     

Systematic risk estimation in the presence of large and many outliers

It is well recognized that the effect of extreme points on systematic risk estimates is not adequately captured through least squares estimation. This article uses the reweighted least median squares (RWLMS) approach, first proposed by Rousseeuw (1984), which accurately detects outlier presence. Using a large sample of 1350 NYSE/AMEX firms, the article demonstrates that least squares does indeed mask several potentially influential points, that this masking is very pervasive over the sample, and that it may persist even after conventional robust estimation techniques are applied. When these masked points are “unmasked” by RWLMS and zero weights assigned to such observations, the resulting RWLMS estimates of beta are on average 10%–15% smaller. However, a Bayesian treatment of such points (assigning a priori nonzero weights) is possible in both one and two factor market models.     

Inequality,public good provision and the composition of trade

This paper investigates the effect of trade liberalization on the provision of public goods and shows that inequality also plays a vital role here. Public goods help enhance the productivity of firms, lower prices and raise profitability. The provision of public goods has different effects in closed and open economies. In an open economy, the impact of productive spending on increasing profit is stronger. Consequently, the opening up of the economy shifts the benefits of productive public goods from consumers to firms. As the median voters’, share of the firm’s profit rises, public goods become more appealing and flourish. Consequently, the manufacturing export is boosted by a rise in productivity.