共查询到20条相似文献,搜索用时 15 毫秒
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Logically defined outcomes are commonly used in medical diagnoses and epidemiological research. When missing values in the original outcomes exist, the method of handling the missingness can have unintended consequences, even if the original outcomes are missing completely at random. In this note, we consider 2 binary original outcomes, which are missing completely at random. For estimating the prevalence of a logically defined "or" outcome, we discuss the properties of 4 estimators: the complete-case estimator, the available-case estimator, the maximum likelihood estimator (MLE), and a moment-based estimator. With the exception of the available-case case estimator, all the estimators are consistent. The MLE exhibits superior performance and should be generally adopted. 相似文献
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A Buckley-James-type estimator for the mean with censored data 总被引:2,自引:0,他引:2
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AGARWAL and KUMAR (1980) proposed an estimator, combining ratio and pps estimators of population mean and proved that the proposed estimator would always be better (in minimum mean square error sense) than the pps estimator or the ratio estimator under pps sampling scheme for optimum value of constant k (parameter). The optimum value of k is rarely known in practice, hence the alternative is to replace k from the sample-values. In this paper, an estimator depending on estimated optimum value of k based on sample-values, under pps sampling scheme is proposed and studied. 相似文献
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P. Kaur 《Biometrical journal. Biometrische Zeitschrift》1985,27(7):831-835
For the estimation of finite population variance of a character, DAS and TRIPATHI (1978) proposed some efficient estimators when population mean of variance of some other character (associated with main character) is known. We propose here some estimators for population variance using same information and compare with those given by DAS and TRIPATHI (1978). Some examples are given for illustration. 相似文献
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Estimating the loss of estimators of a binomial parameter 总被引:2,自引:0,他引:2
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The derivation of the restricted intra-sire regression heritability estimator is provided. Procedures for obtaining a stable estimate of residual error variance σ2 are outlined. A small illustration based on live data is given. 相似文献
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We derive a first-order bias-corrected maximum likelihood estimator for the negative binomial dispersion parameter. This estimator is compared, in terms of bias and efficiency, with the maximum likelihood estimator investigated by Piegorsch (1990, Biometrics46, 863-867), the moment and the maximum extended quasi-likelihood estimators investigated by Clark and Perry (1989, Biometrics45, 309-316), and a double-extended quasi-likelihood estimator. The bias-corrected maximum likelihood estimator has superior bias and efficiency properties in most instances. For ease of comparison we give results for the two-parameter negative binomial model. However, an example involving negative binomial regression is given. 相似文献
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R. Karan Singh 《Biometrical journal. Biometrische Zeitschrift》1983,25(2):193-200
For estimating finite population variance σy2 of a character y under our study, estimators using auxiliary information on a character x in the form of ratio, product, ratio-type or product-type estimators have been suggested, and their comparative study with the conventional unbiased estimator sy2 of σy2 has been made in simple random sampling with replacement. A generalized estimator representing a class of estimators for the finite populations variance, has also been studied. 相似文献
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This paper generalizes the results of AGARWAL (1980) and AGARWAL and KUMAR (1985) by constructing a multivariate ratiotype estimator which, to a first order of approximation, is as efficient as the regression estimator. 相似文献
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This article presents an industrial case study, examining the application of a novel adaptive biomass estimator to an industrial microfungi production process. It is our intention that this contribution should focus upon the implementation issues of the algorithm, in preference to a rigorous theoretical development. The novel algorithm adopted is developed from Adaptive Inferential Estimation studies of Guilandoust and co-workers. The technique utilizes input-output process measurements obtained at different frequencies, thereby providing more frequent estimates of biomass concentration than are otherwise available from off-line laboratory analyses. The algorithm is particularly suited to the biotechnology industry, as it is capable of utilizing irregular assay measurements with varying delays.Although this article demonstrates the encouraging industrial implications of the adaptive algorithm, like all adaptive techniques currently developed, it is restricted by the inability to perform robust on-line system identification. The ultimate selection of a "suboptimal" "fixed parameter" algorithm for on-line implementation, is therefore directly attributable to these inadequacies. Aspects of data acquisition, data pretreatment, and data quality are critical for real process applications, and while some practical approaches are adopted here, many important implementation problems remain unresolved. (c) 1993 John Wiley & Sons, Inc. 相似文献
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Victoire Tankou Sudhakar Dharmadhikari 《Biometrical journal. Biometrische Zeitschrift》1989,31(7):795-802
This paper proposes a method for using multi-auxiliary information at both the design and the estimation stages of a sample survey. The proposed method is an extension of the classical multivariate method of Olkin (1958). The results of Agarwal and Kumar (1978) come out as a special case. 相似文献
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Estimation of variance of the ratio estimator 总被引:5,自引:0,他引:5
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Y. P. Chaubey M. Singh T. D. Dwivedi 《Biometrical journal. Biometrische Zeitschrift》1984,26(4):465-467
This note points out the derivation of regression estimator through an optimality consideration over a class of estimators generating Generalised Product and dual to ratio estimators. 相似文献
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A theorem of Jacobi and its generalization 总被引:1,自引:0,他引:1