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91.
The optimality of two-factor experimental designs is studied in the dual senses of estimating contrasts in the parameters for each of the factors. The outline of comparison employed allows one to judge the performance of different designs for estimating contrasts of one set of parameters directly with the performance of the complementary set without going through a common intermediary step of considering all the parameters. The results hold for a wide class of optimality criteria (not merely D-, A- and E-optimality), which must satisfy a functional equation obtained in connection with our method. Also we investigate the optimality of row–column designs which satisfy an ‘adjusted orthogonality’ condition. Our point of departure is the paper by Shah, Raghavarao and Khatri (1976) and that of Mitchell and John (1977). 相似文献
92.
Thomas J. Santner 《Journal of statistical planning and inference》1981,5(1):45-55
This paper considers the problem of devising a single stage procedure for selecting the treatment combination associated with the largest interaction in a two-factor rfx× c experiment having independent normally distributed observations with common known variance. The intuitive procedure based on the best linear unbiased estimators of the population interactions is employed. Initially an indifference zone formulation is used; the problem of determining the least favorable configuration is reduced to a nonlinear programming problem with log concave objective function and a convex polytope as feasible region. A solution technique is introduced in the context of an illustrative example. The problem is also considered using a preferred population formulation; this approach requires a strengthened version of the indifference zone probability requirement. It is shown that the same sample size guarantees this requirement as does the earlier one. 相似文献
93.
This paper deals with the construction of optimum partitions
of
for a clustering criterion which is based on a convex function of the class centroids
as a generalization of the classical SSQ clustering criterion for n data points. We formulate a dual optimality problem involving two sets of variables and derive a maximum-support-plane (MSP) algorithm for constructing a (sub-)optimum partition as a generalized k-means algorithm. We present various modifications of the basic criterion and describe the corresponding MSP algorithm. It is shown that the method can also be used for solving optimality problems in classical statistics (maximizing Csiszárs
-divergence) and for simultaneous classification of the rows and columns of a contingency table. 相似文献
94.
Harold Sackrowitz 《Journal of statistical planning and inference》1982,6(3):287-296
The problem is that of estimating the probabilities of m independent binomial random variables when their probabilities are known to be nondecreasing and the loss function is squared error. In the cases where the m.l.e. is inadmissible (essentially when the total number of trials is 7 or more) we present a method for modifying the m.l.e. to get a better estimator. The method requires a series of changes. At each step we alter the action taken by the m.l.e. on each of three, appropriately chosen, points in the sample space. 相似文献
95.
V.K. Srivastava 《Journal of statistical planning and inference》1982,6(3):297-299
This paper presents a class of estimators for the mean of a normal population and determines the conditions on characterizing scalars under which the class of estimators uniformly dominates over the conventional sample mean according to the mean-square-error criterion. 相似文献
96.
We consider a life testing situation in which systems are subject to failure from independent competing risks. Following a failure, immediate (stage-1) procedures are used in an attempt to reach a definitive diagnosis. If these procedures fail to result in a diagnosis, this phenomenon is called masking. Stage-2 procedures, such as failure analysis or autopsy, provide definitive diagnosis for a sample of the masked cases. We show how stage-1 and stage-2 information can be combined to provide statistical inference about (a) survival functions of the individual risks, (b) the proportions of failures associated with individual risks and (c) probability, for a specified masked case, that each of the masked competing risks is responsible for the failure. Our development is based on parametric distributional assumptions and the special case for which the failure times for the competing risks have a Weibull distribution is discussed in detail. 相似文献
97.
We analyse post-war Dutch migration to New Zealand. We document that history, reflect on analytical and econometric modelling and then combine a sample of Dutch migrants in New Zealand with a representative sample of Dutch in The Netherlands to estimate wage equations and the determinants of the migration decision. We use the results for ex post evaluation of the migration decision.Joop Hartog is Fellow of IZA (Bonn), CESifo (München), AIAS and Tinbergen Institute (Amsterdam). Work on this project was begun when Hartog was Erskine Visitor at the University of Canterbury, Christchurch New Zealand. Rainer Winkelmann is Fellow of CEPR and IZA (Bonn). This paper is produced as part of a CEPR research programme on European Migration from Economic Analysis to Policy Response, supported by a grant from the Commission of the European Communities under its Human Capital and Mobility Programme (no. ERBCHRXCT940515).It was presented at the European Society for Population Economics meetings in Bonn, June 2000. We gratefully acknowledge comments by Justin Lee Tobias, Jacques Poot, Ed Vytlacil, an anonymous referee and Paul Schultz. Responsible editor: T. Paul Schultz. 相似文献
98.
99.
Claude F. Bennett 《Evaluation and program planning》1984,7(2):115-125
Evaluating an innovation for federal, state, and local policymakers and program managers alike entails conflicting demands on the evaluation study. Policymakers at federal, state, and local levels are best assisted by impact evaluations, whereas state and local program managers are best assisted by process evaluations. In-house evaluators often have an advantage in conducting process evaluations; external evaluators generally have an advantage in conducting impact evaluations. A cost-effective approach may be to combine in-house process evaluation and external impact evaluation. This dual approach was found to reduce conflicting demands on the evaluation of an experimental videotex system for agricultural producers. 相似文献
100.
"2+1"顶岗实习的长效机制研究——以物流管理专业为例 总被引:1,自引:0,他引:1
"2+1"顶岗实习有利于培养学生的职业技能和职业素养,为今后的工作打下良好的基础.文章从运行机制、保障机制和评价机制三个方面探讨顶岗实习长效机制的建立,解决实施过程中存在的问题. 相似文献