Testing spatial randomness based on empirical distribution function: A study on lattice data

In this article, we extended the empirical distribution function based test statistic _Ik$I_k$ of Skaug and Tjostheim [1993. Nonparametric test of serial independence based on the empirical distribution function. Biometrika 80, 591–602] in the time series setting to _Dn$D_n$ for spatial lattice data and derived the asymptotic distribution of the proposed test statistic _Dn$D_n$ under the null hypothesis of spatial independence. The size and power of the proposed test statistic under conditional autoregressive model (CAR) were simulated. We applied _Dn$D_n$, Moran's I and Geary's c   to the transformed and well-studied sudden infant death syndrome data from North Carolina and found that _Dn$D_n$ produced a much smaller p$p$-value in testing spatial independence.     

Conditional moving linear regression: Modeling the recruitment process for ALLHAT

Effective recruitment is a prerequisite for successful execution of a clinical trial. ALLHAT, a large hypertension treatment trial (N = 42,418), provided an opportunity to evaluate adaptive modeling of recruitment processes using conditional moving linear regression. Our statistical modeling of recruitment, comparing Brownian and fractional Brownian motion, indicates that fractional Brownian motion combined with moving linear regression is better than classic Brownian motion in terms of higher conditional probability of achieving a global recruitment goal in 4-week ahead projections. Further research is needed to evaluate how recruitment modeling can assist clinical trialists in planning and executing clinical trials.     

Association of educational level and child sex ratio in rural and urban India

Utilizing data from the Census of India, this study compared child sex ratio in rural and urban regions of India and analyzed whether the child sex ratio was associated with mother’s education level. The child sex ratios in the rural and urban regions throughout India were analyzed using the two-sample and paired Student’s t-test. Further, the Chi-square test for trend in binomial proportions was used to assess the association between child sex ratios and mother’s education levels in rural and urban areas. Analysis of the data showed that there was a significant difference between the child sex ratios in rural areas versus urban areas. In addition, the Chi-square test for trend showed that there was a significant association of the child sex ratio and the educational levels of their mothers. This trend occurred in both rural and urban areas.     

考虑间接网络外部性的电商平台纵向整合策略

考虑双边市场供需规模带来的间接网络外部性影响,全文比较了分散型服务链、平台集中分销业务的局部集中型服务链、平台集中物流业务的局部集中型服务链,以及平台同时控制分销与物流业务的全集中型服务链四种电商服务链结构下的商品价格、双边供需规模和平台利润。计算结果表明,当网购者对网商的间接网络外部效应偏强且高于网商的间接网络外部效应时,电商平台对电商服务链纵向业务的整合力度越强,尤其是涉及到物流业务的整合程度越深,平台的商品价格就越低,双边用户的供需规模会越大,平台的利润会越高。因此,电商平台关于电商服务链的最佳整合策略是采取同时控制分销渠道与物流渠道的全集中型结构。     

Operating Characteristics for Group Sequential Trials Monitored Under Fractional Brownian Motion

Brownian motion has been used to derive stopping boundaries for group sequential trials, however, when we observe dependent increment in the data, fractional Brownian motion is an alternative to be considered to model such data. In this article we compared expected sample sizes and stopping times for different stopping boundaries based on the power family alpha spending function under various values of Hurst coefficient. Results showed that the expected sample sizes and stopping times will decrease and power increases when the Hurst coefficient increases. With same Hurst coefficient, the closer the boundaries are to that of O'Brien-Fleming, the higher the expected sample sizes and stopping times are; however, power has a decreasing trend for values start from H = 0.6 (early analysis), 0.7 (equal space), 0.8 (late analysis). We also illustrate study design changes using results from the BHAT study.     

信息人社会的“纠结”与“给力”--信息人社会与势科学理论研究之五

信息化社会以来,中国文化的复杂性有增无减,阐述这种复杂性的一个重要关键词就是“纠结”。纠结的根源是主体占有的信息量小于环境对象的信息量,纠结的本质是主体信息缺失导致的不确定性。“给力”的本质就是主体得到了信息而产生的确定性,确定性与不确定性的根本问题是信息的相互作用。信息可以归结为有序,复杂在本质上是信息急剧增长的结果,面对社会日趋复杂带来的种种纠结,人类唯一有效的应对战略就是信息战略。应对中国复杂文化纠结的根本路径,就是在社会管理过程中的每一个层次和每一个环节中,通过纠结变换,将作为纠结的约束打开,从而大大缩小交易成本,实现卓有成效的社会管理。     

A note on asymptotic distribution of permutation statistics from mixing processes

The permutation statistics from a-mixing processes with random, symmetric weights are studied The asymptotic distribution of the permutation statistics is derived.     

Fractional Brownian motion and clinical trials

The purpose of this paper is to extend the widely used classical Brownian motion technique for monitoring clinical trial data to a larger class of stochastic processes, i.e. fractional Brownian motion, and compare these results. The beta-blocker heart attack trial is presented as an example to illustrate both methods.     

Asymptotic Distribution of the Estimated BDS Statistic from The Residuals of Location-Scale Type Processes

We introduce local asymptotic normality (LAN) for the log-likelihood ratio and the contiguity property of a class of location-scale processes in this paper. Using the contiguity property, we study the asymptotic distribution of the estimated Brock-Dechert-Scheinkman (BDS) statistic from the standardized residuals of fitting location-scale type processes.     

直销渠道开通的情形下制造商与电商平台合约选择的研究

理论界认为代售合约具有明显的消除双重边际效应的作用,许多制造商和电商平台选择签订代售合约,但是也有制造商和电商平台选择了批发合约。本文以在线销售系统为背景,研究了直销渠道开通的情形下制造商和电商平台合约的选择。通过研究发现,制造商和电商平台并不是总偏好批发合约或代售合约,并且存在一个帕累托改进区域;虽然制造商在电商平台上有网络销售渠道,但是制造商会保留原有的直销渠道;对于电商平台来说,收益分配系数并不是越大越好;代售合约虽然能够消除双重边际效应,但在代售合约下,整个在线销售系统的效率并不总是最高的。另外,随着直销渠道的效率增加,制造商会先降低批发价格,然后再增加批发价格;与以往的研究结论不同,代售合约下电商平台的市场销售价格并不总是最小的。以上的结论其实都是批发合约下的直销渠道和代售合约下的电商平台在缓解双重边际效应方面的不同作用带来的。