Tests for the multivariate two-sample problem based on empirical probability measures

Nonparametric tests are proposed for the equality of two unknown p-variate distributions. Empirical probability measures are defined from samples from the two distributions and used to construct test statistics as the supremum of the absolute differences between empirical probabilities, the supremum being taken over all possible events. The test statistics are truly multivariate in not requiring the artificial ranking of multivariate observations, and they are distribution-free in the general p-variate case. Asymptotic null distributions are obtained. Powers of the proposed tests and a competitor are examined by Monte Carlo techniques.     

A Note on an Unbiased Test of Homogeneity of Variances

A necessary and sufficient condition for unbiasedness of the test of homogeneity of variances in normal samples is derived in a convenient form. In the case of two samples, it is shown that Bartlett's test is the only unbiased test of homogeneity of variances. A simple alternative proof of the unbiasedness of Bartlett's test in the general case is also provided.     

中韩创新对出口贸易的影响比较——以专利为视点的实证研究

创新是知识经济时代的特征,是一国竞争力的主要源泉,专利授予量则是衡量一国创新状况的最好指标。在经济一体化的今天,一国的经济实力和该国的贸易状况有着密切的关系。通过EG协整检验、因果关系检验等方法,验证代表一国创新水平的专利尤其是发明专利对外贸出口的直接拉动效应。实证分析显示,在韩国,创新活动在增加出口方面扮演更重要的角色。这表明,一国竞争力的提高关键是自主创新能力的提升。     

当代大学生对女性印象内隐实验研究

本实验采用内隐联结测验（IAT）,回避社会赞许效应等干扰因素,考察了当代大学生对于女性印象的内隐态度,发现他们更认同与现代女性形象即他们女性印象是积极地,独立自主的。且这种内隐认同态度不存在性别差异、城乡差异及文理科差异。     

On Reading Test

There has been a long discussion over the construct validity of reading tests. In china's reading tests, multiple choice is the main test method in view of the4 long controversy over the validity of multiple choice, construct validation is called for to empirically test the hypothesized relationships between test scores and abilities. The national CET committee conducted a comprehensive validation study. As part of the project, the specialists studied the reading comprehension test' s validity by qualitative means, namely "introspective verbal reports". The analysis revealed that an overwhelming majority of the questions items were handled through "expected reading operations".     

A pragmatic adaptive enrichment design for selecting the right target population for cancer immunotherapies

One of the challenges in the design of confirmatory trials is to deal with uncertainties regarding the optimal target population for a novel drug. Adaptive enrichment designs (AED) which allow for a data-driven selection of one or more prespecified biomarker subpopulations at an interim analysis have been proposed in this setting but practical case studies of AEDs are still relatively rare. We present the design of an AED with a binary endpoint in the highly dynamic setting of cancer immunotherapy. The trial was initiated as a conventional trial in early triple-negative breast cancer but amended to an AED based on emerging data external to the trial suggesting that PD-L1 status could be a predictive biomarker. Operating characteristics are discussed including the concept of a minimal detectable difference, that is, the smallest observed treatment effect that would lead to a statistically significant result in at least one of the target populations at the interim or the final analysis, respectively, in the setting of AED.     

Sample size calculation for logrank test and prediction of number of events over time

We review and compare existing methods for sample size calculation based on the logrank statistic and recommend the method of Lakatos for its accuracy and flexibility in allowing time-dependent rates of event, loss to follow-up, and noncompliance. We extend the Lakatos method to allow a general follow-up scheme, to handle non-inferiority tests, and to predict the number of events over calendar time. We apply the Lakatos method to the simple nonproportional hazard situation of delayed treatment effect to facilitate the comparison of different weighting methods and to evaluate the performance of the maximum combination tests. We use simulation studies to confirm the validity of the Lakatos method and its extensions.     

时间断点回归:原理框架、应用演进与估计流程

文章首先运用归纳法,提出时间断点回归的概念内涵和基本模型,并按"准随机实验"标准分析其存在的原理缺陷。然后通过梳理国外相关前沿成果,总结出时间断点回归有别于传统计量操作的方面:在适用性判断上,强调内生分组问题的理论分析和协变量连续性的提前估计;在稳定性检验上,包含更换变量指标等正向思路、对照组检验等反向思路、时间序列特征处理和其他非断点回归方法。最后,绘制时间断点回归的估计流程图,主要涉及适用性检验、处理效应的初步判定、模型构建与估计和稳健性检验四个部分。     

Estimating the Technology of Cognitive and Noncognitive Skill Formation

This paper formulates and estimates multistage production functions for children's cognitive and noncognitive skills. Skills are determined by parental environments and investments at different stages of childhood. We estimate the elasticity of substitution between investments in one period and stocks of skills in that period to assess the benefits of early investment in children compared to later remediation. We establish nonparametric identification of a general class of production technologies based on nonlinear factor models with endogenous inputs. A by‐product of our approach is a framework for evaluating childhood and schooling interventions that does not rely on arbitrarily scaled test scores as outputs and recognizes the differential effects of the same bundle of skills in different tasks. Using the estimated technology, we determine optimal targeting of interventions to children with different parental and personal birth endowments. Substitutability decreases in later stages of the life cycle in the production of cognitive skills. It is roughly constant across stages of the life cycle in the production of noncognitive skills. This finding has important implications for the design of policies that target the disadvantaged. For most configurations of disadvantage it is optimal to invest relatively more in the early stages of childhood than in later stages.