Sample Size Calculation for the Therapeutic Equivalence Problem

A method is proposed for the sample size calculation in the case of therapeutic equivalence of two pharmaceuticals, when the decision is based on post-treatment differences and the post-treatment values are dependent on the pretreatment ones. When the correlation coefficient is large (over 0.7), it is shown that sample size calculation (and the corresponding hypothesis test) based on the sample statistic formed by the mean difference of the post–pre differences of each group has smaller variance and hence leads to smaller sample sizes.     

A Revisit to the Behrens–Fisher Problem: Comparison of Five Test Methods

We revisit the well-known Behrens–Fisher problem and apply a newly developed ‘Computational Approach Test’ (CAT) to test the equality of two population means where the populations are assumed to be normal with unknown and possibly unequal variances. An advantage of the CAT is that it does not require the explicit knowledge of the sampling distribution of the test statistic. The CAT is then compared with three widely accepted tests—Welch–Satterthwaite test (WST), Cochran–Cox test (CCT), ‘Generalized p-value’ test (GPT)—and a recently suggested test based on the jackknife procedure, called Singh–Saxena–Srivastava test (SSST). Further, model robustness of these five tests are studied when the data actually came from t-distributions, but wrongly perceived as normal ones. Our detailed study based on a comprehensive simulation indicate some interesting results including the facts that the GPT is quite conservative, and the SSST is not as good as it has been claimed in the literature. To the best of our knowledge, the trends observed in our study have not been reported earlier in the existing literature.     

Testing the Equality of the Noncentrality Parameters of Two Noncentral t-Distributions with Identical Degrees of Freedom

The problem of testing the equality of the noncentrality parameters of two noncentral t-distributions with identical degrees of freedom is considered, which arises from the comparison of two signal-to-noise ratios for simple linear regression models. A test procedure is derived that is guaranteed to maintain Type I error while having only minimal amounts of conservativeness, and comparisons are made with several other approaches to this problem based on variance stabilizing transformations. The new procedure derived in this article is shown to have good properties and will be useful for practitioners.     

Do greater amounts of FDI cause higher pollution levels? Evidence from OECD countries

Using an ARDL model for a panel of 15 OECD countries, this work analyses the impact that FDI, both jointly and by sector, has on CO₂ emissions. The findings reveal that these countries are yielding to the pressure on the trade sector. Unexpectedly, gross fixed capital formation shrink pollution, excluding in the mining sector. With findings supporting the Pollution Haven Hypothesis, policymakers must pay attention to FDI inflows, ensuring that FDI place high importance on the transfer of green technologies to improve the efficiency. These goals could be achieved through an increase in the stringency of environmental laws within the host countries, especially the ones related to FDI.     

Modeling of Discrete HNBUE Class with Hypothesis Testing Application

A new model is proposed to test whether an equipment whose life is measured in discrete time units fails due to uncontrollable chance factors alone against the alternatives that it degrades over time in the sense of discrete HNBUE (harmonic new better than used in expectation) aging. The test is shown to be consistent and the asymptotic distribution of the test statistic has been obtained. The critical points and the power of the test against various alternatives from discrete HNBUE class have been studied by means of simulation. Finally, the test is applied to a discrete reliability data to examine the performance.     

A Shiny Update to an Old Experiment Game

ABSTRACT

Games can be a powerful tool for learning about statistical methodology. Effective game design involves a fine balance between caricature and realism, to simultaneously illustrate salient concepts in a controlled setting and serve as a testament to real-world applicability. Striking that balance is particularly challenging in response surface and design domains, where real-world scenarios often play out over long time scales, during which theories are revised, model and inferential techniques are improved, and knowledge is updated. Here, I present a game, borrowing liberally from one first played over 40 years ago, which attempts to achieve that balance while reinforcing a cascade of topics in modern nonparametric response surfaces, sequential design, and optimization. The game embeds a blackbox simulation within a shiny app whose interface is designed to simulate a realistic information–availability setting, while offering a stimulating, competitive environment wherein students can try out new methodology, and ultimately appreciate its power and limitations. Interface, rules, timing with course material, and evaluation are described, along with a “case study” involving a cohort of students at Virginia Tech. Supplementary materials for this article are available online.     

我院96级专科学生英语学习成绩研究与分析

为了更详细地了解学生的英语学习情况,以增强和促进我院的专科英语教学,本文对我院96级学生的英语学习成绩用统计中的回归分析和假设检验进行了统计和分析,并提出了三点建议。     

An Adaptive,Rate‐Optimal Test of a Parametric Mean‐Regression Model Against a Nonparametric Alternative

We develop a new test of a parametric model of a conditional mean function against a nonparametric alternative. The test adapts to the unknown smoothness of the alternative model and is uniformly consistent against alternatives whose distance from the parametric model converges to zero at the fastest possible rate. This rate is slower than n^−1/2. Some existing tests have nontrivial power against restricted classes of alternatives whose distance from the parametric model decreases at the rate n^−1/2. There are, however, sequences of alternatives against which these tests are inconsistent and ours is consistent. As a consequence, there are alternative models for which the finite‐sample power of our test greatly exceeds that of existing tests. This conclusion is illustrated by the results of some Monte Carlo experiments.     

人口年龄结构、经济增长与中国居民消费

本文以生命周期假说为理论基础,运用中国2002-2008年的省级面板数据分析了人口年龄结构变化和经济增长对中国居民消费率的影响.实证研究发现:人口结构因素和收入增长率对居民消费有着显著的影响.其中,消费率与少儿抚养比、老年抚养比间分别存在正相关关系和负相关关系,与经济增长率之间存在负相关关系.然而,在分别对东、中、西部地区的研究中却发现,消费率与抚养比以及经济增长率的关系并不与全国保持一致,这些差别反映了区域间经济社会发展差距以及不同地区老龄化程度的差异.     

结构参数、出口固定投入成本与贸易扩展边际

替代弹性和异质性参数是决定出口固定投入成本对扩展边际影响程度的关键因素。本文借鉴异质性企业贸易理论分析框架,推导出能反应市场结构的结构引力模型,并使用2004-2007年的面板数据对中国制造业29个产业的出口进行实证分析,在此基础上对10个产业的结构参数（替代弹性和异质性参数）进行估计,并考察出口固定投入成本对总出口和扩展边际影响的程度。结果发现,大部分产业（29个产业中有22个）结构引力模型系数的估计结果符合理论预期;对10个产业结构参数的估计也同理论预期一致;出口固定投入成本对总出口和扩展边际的影响因产业的不同而不同。政策含义上意味着贸易便利化政策和产业政策应相互结合,保证贸易平稳健康发展。