排序方式: 共有76条查询结果,搜索用时 62 毫秒
11.
C.Y. Leung 《统计学通讯:理论与方法》2013,42(11):3869-3880
The plug–in Anderson's covariate classification statistic is constructed on the basis of an initially unclassified training sample by means of posty–stratification. The asymptotic efficiency relative to the discriminant based on an initially classified training sample is evaluated for the case where a covariate is present. Effect of post–stratification is examined. 相似文献
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This article considers misclassification of categorical covariates in the context of regression analysis; if unaccounted for, such errors usually result in mis-estimation of model parameters. With the presence of additional covariates, we exploit the fact that explicitly modelling non-differential misclassification with respect to the response leads to a mixture regression representation. Under the framework of mixture of experts, we enable the reclassification probabilities to vary with other covariates, a situation commonly caused by misclassification that is differential on certain covariates and/or by dependence between the misclassified and additional covariates. Using Bayesian inference, the mixture approach combines learning from data with external information on the magnitude of errors when it is available. In addition to proving the theoretical identifiability of the mixture of experts approach, we study the amount of efficiency loss resulting from covariate misclassification and the usefulness of external information in mitigating such loss. The method is applied to adjust for misclassification on self-reported cocaine use in the Longitudinal Studies of HIV-Associated Lung Infections and Complications. 相似文献
13.
The product limit or Kaplan‐Meier (KM) estimator is commonly used to estimate the survival function in the presence of incomplete time to event. Application of this method assumes inherently that the occurrence of an event is known with certainty. However, the clinical diagnosis of an event is often subject to misclassification due to assay error or adjudication error, by which the event is assessed with some uncertainty. In the presence of such errors, the true distribution of the time to first event would not be estimated accurately using the KM method. We develop a method to estimate the true survival distribution by incorporating negative predictive values and positive predictive values, into a KM‐like method of estimation. This allows us to quantify the bias in the KM survival estimates due to the presence of misclassified events in the observed data. We present an unbiased estimator of the true survival function and its variance. Asymptotic properties of the proposed estimators are provided, and these properties are examined through simulations. We demonstrate our methods using data from the Viral Resistance to Antiviral Therapy of Hepatitis C study. 相似文献
14.
In this paper, we consider the Bayesian analysis of binary time series with different priors, namely normal, Students' t, and Jeffreys prior, and compare the results with the frequentist methods through some simulation experiments and one real data on daily rainfall in inches at Mount Washington, NH. Among Bayesian methods, our results show that the Jeffreys prior perform better in most of the situations for both the simulation and the rainfall data. Furthermore, among weakly informative priors considered, Student's t prior with 7 degrees of freedom fits the data most adequately. 相似文献
15.
The reconstruction of phylogenetic trees is one of the most important and interesting problems of the evolutionary study. There are many methods proposed in the literature for constructing phylogenetic trees. Each approach is based on different criteria and evolutionary models. However, the topologies of trees constructed from different methods may be quite different. The topological errors may be due to unsuitable criterions or evolutionary models. Since there are many tree construction approaches, we are interested in selecting a better tree to fit the true model. In this study, we propose an adjusted k-means approach and a misclassification error score criterion to solve the problem. The simulation study shows this method can select better trees among the potential candidates, which can provide a useful way in phylogenetic tree selection. 相似文献
16.
Christina Maags 《Social Policy & Administration》2021,55(1):113-127
Although the party‐state has embarked on a mission to increase elder care services, evaluating this development according to different sectors demonstrates certain challenges. Official statistics do not include sector‐specific information, and while provider websites suggest that elder care services are largely in public hands, Chinese experts argue that they are mostly “civilian‐run.” How can we explain these discrepancies in data on Chinese elder care? Drawing on the concept of hybridization and triangulating quantitative and qualitative data, I argue that the party‐state's efforts to “socialize” elder care provision has resulted in hybridization within the industry which blurs the line between care providers and obfuscates the stark role of the state in elder care service provision. During the implementation of state‐initiated hybridization, providers misclassify their ownership type to benefit from financial incentives or circumvent political control, resulting in even greater hybridization and fragmentation on the ground. 相似文献
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18.
Aprajit Mahajan 《Econometrica : journal of the Econometric Society》2006,74(3):631-665
This paper studies the problem of identification and estimation in nonparametric regression models with a misclassified binary regressor where the measurement error may be correlated with the regressors. We show that the regression function is nonparametrically identified in the presence of an additional random variable that is correlated with the unobserved true underlying variable but unrelated to the measurement error. Identification for semiparametric and parametric regression functions follows straightforwardly from the basic identification result. We propose a kernel estimator based on the identification strategy, derive its large sample properties, and discuss alternative estimation procedures. We also propose a test for misclassification in the model based on an exclusion restriction that is straightforward to implement. 相似文献
19.
The most popular goodness of fit test for a multinomial distribution is the chi-square test. But this test is generally biased if observations are subject to misclassification, In this paper we shall discuss how to define a new test procedure when we have double sample data obtained from the true and fallible devices. An adjusted chi-square test based on the imputation method and the likelihood ratio test are considered, Asymptotically, these two procedures are equivalent. However, an example and simulation results show that the former procedure is not only computationally simpler but also more powerful under finite sample situations. 相似文献
20.
《Journal of Statistical Computation and Simulation》2012,82(9):2025-2043
In this paper, the expected total costs (ETCs) of three kinds of quality cost functions for the two-sided sequential screening procedure (SQSP) based on the individual misclassification error are obtained, where the ETC is the sum of the expected cost of inspection, the expected cost of rejection and the expected cost of quality. The general formulas for all the desired probabilities and three ETCs when k screening variables are allocated into r-stages are derived. The optimal allocation combination for each ETC is determined based on the criterion of minimum ETC. Finally, we give two examples to illustrate the selection of the optimal allocation combination for the SQSP. 相似文献