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Divakar Sharma 《统计学通讯:理论与方法》2013,42(5):611-623
Suppose an estimation problem is invariant under a group of transformations and one is interested in finding an optimal equivariant estimator. The usual proactice is to confine attention to non-randomized equivariant estimators based on a minimal sufficient statistic. A justification of this restriction to a smaller clas of estimators is given in this paper under certain conditions. 相似文献
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For estimating the common mean of a bivariate normal distribution, Krishnamoorthy & Rohatgi (1989) proposed some estimators which dominate the maximum likelihood estimator in a large region of the parameter space. We consider some modifications of these estimators and study their risk performance. 相似文献
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Let πi(i=1,2,…K) be independent U(0,?i) populations. Let Yi denote the largest observation based on a random sample of size n from the i-th population. for selecting the best populaton, that is the one associated with the largest ?i, we consider the natural selection rule, according to which the population corresponding to the largest Yi is selected. In this paper, the estimation of M. the mean of the selected population is considered. The natural estimator is positively biased. The UMVUE (uniformly minimum variance unbiased estimator) of M is derived using the (U,V)-method of Robbins (1987) and its asymptotic distribution is found. We obtain a minimax estimator of M for K≤4 and a class of admissible estimators among those of the form cYmax. For the case K = 2, the UMVUE is improved using the Brewster-Zidek (1974) Technique with respect to the squared error loss function L1 and the scale-invariant loss function L2. For the case K = 2, the MSE'S of all the estimators are compared for selected values of n and ρ=?1/(?1+?2). 相似文献
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Divakar Rajamani H. Neil Geismar Chelliah Sriskandarajah 《Production and Operations Management》2006,15(4):544-552
The Federal Reserve System of the United States is making changes to its cash recirculation policy to reduce depository institutions' (banks') overuse of its cash processing services. These changes will affect operating policies and costs at many institutions having large cash businesses and, in turn, impact cash transportation and logistics providers. This study provides the framework to study the cash supply chain structure and analyzes it as a closed‐loop supply chain. Additionally, it describes the cash flow management system used by banks in the U.S. 相似文献
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The problem of estimating ordered parameters is encountered in biological, agricultural, reliability and various other experiments. Consider two populations with densities f1(x1-ω1) and f2(x2-ω2) where ω1#ω2. The estimation of ω1,ω2) with the loss function, the sum of squared errors, is studied. when fi is the fi(,i,,i 2) density with ,i known, i=1,2; we obtain a class of minimax estimators. When ω1 #ω2 we show some of these estimators are improved by the maximum likelihood estimator. For a general fi we give sufficient conditions for the minimaxity of the analogue of the Pitman estimator. 相似文献
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