Testing equality of variances in the analysis of repeated measurements

The problem of comparing the precisions of two instruments using repeated measurements can be cast as an extension of the Pitman-Morgan problem of testing equality of variances of a bivariate normal distribution. Hawkins (1981) decomposes the hypothesis of equal variances in this model into two subhypotheses for which simple tests exist. For the overall hypothesis he proposes to combine the tests of the subhypotheses using Fisher's method and empirically compares the component tests and their combination with the likelihood ratio test. In this paper an attempt is made to resolve some discrepancies and puzzling conclusions in Hawkins's study and to propose simple modifications.
The new tests are compared to the tests discussed by Hawkins and to each other both in terms of the finite sample power (estimated by Monte Carlo simulation) and theoretically in terms of asymptotic relative efficiencies.     

滇南荒田铅锌矿床地质特征及找矿标志

荒田铅矿矿床位于华南褶皱系、扬子准地台和唐古拉-昌都-兰坪-思茅褶皱系三大Ⅰ级构造单元衔接过渡部位,属红河断裂北侧的回新-虾洞-荒田-大冷山铅锌银多金属成矿带南东部。矿区主要出露下二叠统茅口组(P1m)、玄武岩组(P1β)、上三叠统火把冲组(T3h),为一套海相碳酸盐岩-基性火山喷发-沉积岩组合。铅锌矿体赋存于玄武质、灰质角砾岩中并受角砾岩性和厚度控制,富厚部位常在褶皱(背斜)的两翼和向斜的槽部。玄武质、灰质角砾岩层和次级褶皱的两翼、槽部是重要的找矿标志。矿床成因属"火山沉积-岩浆期后热液+后期构造改造富集"。     

中国服务业发展悖论——基于“两波”发展模式的研究

本文借鉴最新文献对服务业发展规律的测度方法,用中国1952—2010年的地区面板数据对我国服务业比重变化的长期规律和阶段性特征进行了测度,结果认为:宏观国家层面上,我国服务业比重的变化确实有悖于世界经济整体服务化的趋势;但在地区层面上,我国服务业比重与人均GDP的关系基本符合"服务业比重随经济发展不断上升"的普遍规律,所谓经济服务化的"中国悖论"在地区层面上并不存在;对服务业发展的阶段性特征和地区差异进行分析发现,我国大部分地区仍然处于以传统服务业为主的第一波发展阶段,只有少数地区进入了以现代服务业发展为主导的第二波。文章最后对我国服务业发展规律的成因进行了一般分析和实证检验。     

The management of acid-related disorders: the burden of disease and the need for effective treatment

Summary

A large and increasing number of people suffer from acid-related disorders such as dyspepsia, gastro-oesophageal reflux disease (GORD), and peptic ulcer disease. In 1994 alone, about 2 million patients consulted their family doctor for an acid-related disorder. Treatment of these patients represents a high cost to the NHS in terms of medications, consultations, referrals and treatment of complications. UK government statistics also indicate that there is a huge economic burden associated with acid-related disorders in terms of lost productivity.

Effective management of acid-related disorders is required to ensure that the available resources are used efficiently and to the benefit of the NHS, society and the patient.

Proton pump inhibitors are the most effective and predictable therapy available for acid-related disorders and many clinical studies have demonstrated their superior efficacy over H2-receptor antagonists in the management of these conditions. These therapeutic advantages translate into economic gains. Several economic studies have shown that it is more cost-effective to treat GORD and peptic ulcer disease with the proton pump inhibitor omeprazole than with H2-receptor antagonists.     

Natural resource dependence, non-tradables, and economic growth

I argue that the commonly used nominal measure of natural resource dependence – the share of exports of primary products in GNP – understates in growth regressions the negative link between natural resource dependence and per capita GDP growth. I show that using a purchasing power parity adjusted measure yields an economically much larger negative relationship between per capita GDP growth and natural resource dependence than what has been suggested by the nominal measure. Consistent with the rent-seeking literature, I show that the resource curse is a symptom of societies characterized by high levels of corruption and sluggish checks and balances on political decision-making.     

农地承包经营权的职能异化与回归

当前,在我国各地广泛实施的农地承包制度正遇到前所未有的尴尬,不能适应二元经济结构变迁的现实,农地制度改革势在必行。目前,我国土地承包经营权的就业与收入职能不断弱化,农村社会保障事业严重滞后。安徽省肥东县农村的31户农户调研数据表明：从公平与效率两个角度分析回归农地生产要素这一根本职能是十分可行和必要的,因此,可以尝试“以土地换保险”的办法回归农地的根本职能。     

浅析连锁便利店之竞争优势

我国连锁便利店自20世纪90年代初开始出现以来,发展迅速,大有星火燎原,全国蔓延之势,但背后蕴藏着潜在的危机和薄弱环节。本文主要阐述连锁便利店如何形成自己的竞争优势,在需求过剩、市场激烈竞争中脱颖而出。     

长株潭国家级烟草物流园竞争力研究

长株潭烟草物流园区作为国民经济的重要基础设施,对振兴湖南烟草行业具有重要的现实意义。文中分析了物流园区的竞争力,进而从技术、制度、规模、人才、交通、经济、低碳等方面对长株潭国家级烟草物流园的竞争力进行了研究。     

ALTERNATIVE WEIGHTING APPROACHES TO COMPUTING INDEXES OF ECONOMIC ACTIVITY

This paper compares the weighting schemes in the traditional, principal component and dynamic factor approaches to summarizing information from a number of component variables. To facilitate the comparison, we propose a framework to discuss the approaches with respect to their implied loadings in a latent variable model. We also propose a way to transform the dynamic factor index into an analogous index which is a weighted average of the components. The framework shows the strengths and weakness of the alternative weighting schemes and the sense in which the dynamic factor approach has the advantage of capturing both the significance and the variability of the components.