Design of a rotation scheme for a stratified multi-stage sample

A rotation scheme for a stratified multi-stage sample, discussed in this paper, was designed to statisfy the following conditions: (i) there is a constraint on the number of units that can be replaced in each round, and (ii) it is relatively inexpensive to increase the sample size gradually. An example of these conditions was observed in the development of a plan for measuring the accuracy of the billing process of a telephone company. Estimators of the population proportion of elements that possess a specified characteristic are also derived. Each estimator is a weighted average of the corresponding estimates based on the retained units from the original sample and on the new units, where the weight of the estimate based on the new units increases over time. While this rotation scheme is discussed in connection with the billing accuracy of a telephone company, the methodology can be applied to other similar problems.     

一类中立型偏微分方程的振动性

本文研究了一类中立型偏微分方程(?)~2 /(?)t~2[u(x,t)+sum from i=1 to m(λ_i(t)u(x,t-τ_i)])+(?)/(?)t[u(x,t)+sum from i=1 to m(λ_i(t)u(x,t-τ_i)])+P(x,t)u(x,t)+sum from j=1 to m_1(P_j(x,t)u(x,t-δ_j))=△u(x,t)+sum from k=1 to m_2(a_k(t)△u(x,t-p_k)(1)解的振动性,其中(x,t)∈Ω×(0,+∞)≡G,Ω(?)R~n是有界域,(?)Ω逐片光滑,△u=sum from k=1 to n((?)~2/(?)x_k~2u(x,t)),我们获得了方程(1)在不同边界条件下的所有解振动的充分条件,并给出这些充分条件应用的实际例子.     

A MODIFICATION OF THE SEQUENTIAL PROBABILITY RATIO TEST FOR TESTING A NORMAL MEAN

A modification of the sequential probability ratio test is proposed in which Wald's parallel boundaries are broken at some preassigned point of the sample number axis and Anderson's converging boundaries are used prior to that. Read's partial sequential probability ratio test can be considered as a special case of the proposed procedure. As far as 'the maximum average sample number reducing property is concerned, the procedure is as good as Anderson's modified sequential probability ratio test.     

Robust Confidence Regions for Incomplete Models

Call an economic model incomplete if it does not generate a probabilistic prediction even given knowledge of all parameter values. We propose a method of inference about unknown parameters for such models that is robust to heterogeneity and dependence of unknown form. The key is a Central Limit Theorem for belief functions; robust confidence regions are then constructed in a fashion paralleling the classical approach. Monte Carlo simulations support tractability of the method and demonstrate its enhanced robustness relative to existing methods.     

Regression Using Pairs vs. Regression on Differences: A Real-life Case Study for a Master's Level Methods Class

When teaching regression classes real-life examples help emphasize the importance of understanding theoretical concepts related to methodologies. This can be appreciated after a little reflection on the difficulty of constructing novel questions in regression that test on concepts rather than mere calculations. Interdisciplinary collaborations can be fertile contexts for questions of this type. In this article, we offer a case study that students will find: (1) practical with respect to the question being addressed, (2) compelling in the way it shows how a solid understanding of theory helps answer the question, and (3) enlightening in the way it shows how statisticians contribute to problem solving in interdisciplinary environments. Supplementary materials for this article are available online.     

制定反倾销策略的一种决策方法研究

研究倾销幅度变化引致的进口国经济和就业的变化对进口国制定反倾销策略有重要参考价值。本文建立了计算倾销对进口国经济直接、关联和完全影响的可计算局部均衡-投入占用产出模型。在该模型的基础上,逐一分析倾销幅度的变化所引起的进口国产业总产出的变化、就业的变化和消费者福利的变化,并给出了它们之间变化关系的经济数学表达式。该研究为制定反倾销策略提供了一种决策方法。