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排序方式: 共有8543条查询结果,搜索用时 15 毫秒
941.
Let X1X2,.be i.i.d. random variables and let Un= (n r)-1S?(n,r) h (Xi1,., Xir,) be a U-statistic with EUn= v, v unknown. Assume that g(X1) =E[h(X1,.,Xr) - v |X1]has a strictly positive variance s?2. Further, let a be such that φ(a) - φ(-a) =α for fixed α, 0 < α < 1, where φ is the standard normal d.f., and let S2n be the Jackknife estimator of n Var Un. Consider the stopping times N(d)= min {n: S2n: + n-1≤2a-2},d > 0, and a confidence interval for v of length 2d,of the form In,d= [Un,-d, Un + d]. We assume that Var Un is unknown, and hence, no fixed sample size method is available for finding a confidence interval for v of prescribed width 2d and prescribed coverage probability α Turning to a sequential procedure, let IN(d),d be a sequence of sequential confidence intervals for v. The asymptotic consistency of this procedure, i.e. limd → 0P(v ∈ IN(d),d)=α follows from Sproule (1969). In this paper, the rate at which |P(v ∈ IN(d),d) converges to α is investigated. We obtain that |P(v ∈ IN(d),d) - α| = 0 (d1/2-(1+k)/2(1+m)), d → 0, where K = max {0,4 - m}, under the condition that E|h(X1, Xr)|m < ∞m > 2. This improves and extends recent results of Ghosh & DasGupta (1980) and Mukhopadhyay (1981). 相似文献
942.
N. I. Fisher 《Australian & New Zealand Journal of Statistics》1986,28(2):213-219
Robust methods are proposed for testing whether several directional distributions on the unit p-sphere have comparable dispersions. The families of distributions considered are the Langevin for random vectors, and the Generalised Scheidegger-Watson for random axes, with specific interest in the Fisher and Watson distributions on the sphere. The methods are analogues of Levene's procedure for comparing variances of normal distributions. 相似文献
943.
Suppose data are collected in a three-mode fashion (individuals x items X attributes), and it is sought to cluster the individuals into groups on the basis of lineat relations between scores on the attributes for each item and auxiliary measurements made on the same items. A mixture model is pro posed and the EM algorithm is used to fit it to the data by simultaneously estimating the group parameters and allocating individuals to groups. The method is illustrated by a simulation study and a real example in which consumers are clustered on the basis of product scores that are related to a sensory laboratory measurement. 相似文献
944.
The set of distinct blocks of a block design is known as its support. We construct complete designs with parameters v(?7), k=3, λ=v ? 2 which contain a block of maximal multiplicity and with support size . Any complete design which contains such a block, and has parameters v, k, λ as above, must be supported on at most (v3) ? 4(v ? 2) blocks. Attention is given to complete designs because of their direct relationship to simple random sampling. 相似文献
945.
R. P. Littlejohn 《Australian & New Zealand Journal of Statistics》1981,23(1):91-94
Expressions are derived for the interval moments of a length-biassed sample from a renewal process of finite length. 相似文献
946.
视频点击流数据挖掘在远程教育中的应用 总被引:1,自引:1,他引:0
Web数据挖掘已经成为数据挖掘技术一个重要的应用领域,文章主要通过对远程教育网站的视频点击流日志文件进行数据挖掘,寻求用户访问规律,构建动态的个性化教育网站. 相似文献
947.
In this paper, we introduce non-centered and partially non-centered MCMC algorithms for stochastic epidemic models. Centered
algorithms previously considered in the literature perform adequately well for small data sets. However, due to the high dependence
inherent in the models between the missing data and the parameters, the performance of the centered algorithms gets appreciably
worse when larger data sets are considered. Therefore non-centered and partially non-centered algorithms are introduced and
are shown to out perform the existing centered algorithms. 相似文献
948.
Abdissa?NegassaEmail author Antonio?Ciampi Michal?Abrahamowicz Stanley?Shapiro Jean-Fran?ois?Boivin 《Statistics and Computing》2005,15(3):231-239
The performance of computationally inexpensive model selection criteria in the context of tree-structured subgroup analysis is investigated. It is shown through simulation that no single model selection criterion exhibits a uniformly superior performance over a wide range of scenarios. Therefore, a two-stage approach for model selection is proposed and shown to perform satisfactorily. Applied example of subgroup analysis is presented. Problems associated with tree-structured subgroup analysis are discussed and practical solutions are suggested. 相似文献
949.
Using the data from the AIDS Link to Intravenous Experiences cohort study as an example, an informative censoring model was
used to characterize the repeated hospitalization process of a group of patients. Under the informative censoring assumption,
the estimators of the baseline rate function and the regression parameters were shown to be related to a latent variable.
Hence, it becomes impractical to directly estimate the unknown quantities in the moments of the estimators for the bandwidth
selection of a smoothing estimator and the construction of confidence intervals, which are respectively based on the asymptotic
mean squared errors and the asymptotic distributions of the estimators. To overcome these difficulties, we develop a random
weighted bootstrap procedure to select appropriate bandwidths and to construct approximated confidence intervals. One can
see that our method is simple and faster to implement from a practical point of view, and is at least as accurate as other
bootstrap methods. In this article, it is shown that the proposed method is useful through the performance of a Monte Carlo
simulation. An application of our procedure is also illustrated by a recurrent event sample of intravenous drug users for
inpatient cares over time. 相似文献
950.
Danny Dyer 《Revue canadienne de statistique》1981,9(1):71-77
By using the structural density function (Fraser 1979, Ch. 7) of the parameters of a Pareto distribution, the structural distribution function of the strong Pareto law is derived. Its fractiles have been evaluated numerically for special cases, and the results are displayed through graphs from which structural one-sided probability bounds may be found. It is shown that these graphs may also be used to find structural tolerance bounds for the Pareto distribution. 相似文献