2006

最新文章

• Estimation of expression indexes for oligonucleotide arrays using the singular value decomposition AI翻译
  作者：Hu, JH; Wright, FA; Zou, F
  作者单位：University of Texas System; UTMD Anderson Cancer Center; University of North Carolina; University of North Carolina Chapel Hill
  摘要：Multiprobe oligonucleotide arrays are a widely used type of expression microarray with the attractive feature that numerous probes are used to represent each transcript. An expression index is a statistic used to represent expression level for a particular gene that is estimated from the probe hybridization intensities. We show that a popular model-based expression index proposed by Li and Wong has an interpretation as a component of the singular value decomposition (SVD) of the probe intensit...
• Optimal and efficient crossover designs when subject effects are random AI翻译
  作者：Hedayat, A. S.; Stufken, John; Yang, Min
  作者单位：University of Illinois System; University of Illinois Chicago; University of Illinois Chicago Hospital; University System of Georgia; University of Georgia; University of Missouri System; University of Missouri Columbia
  摘要：Most studies on optimal crossover designs are based on models that assume subject effects to be fixed effects. In this article we identify and study optimal and efficient designs for a model with random subject effects. With the number of periods not exceeding the number of treatments, we find that totally balanced designs are universally optimal for treatment effects in a large subclass of competing designs. However, in the entire class of designs, totally balanced designs are in general not ...
• Evaluating kindergarten retention policy: A case study of causal inference for multilevel observational data AI翻译
  作者：Hong, Guanglei; Raudenbush, Stephen W.
  作者单位：University of Toronto; University Health Network Toronto; University of Chicago
  摘要：This article considers the policy of retaining low-achieving children in kindergarten rather than promoting them to first grade. Under the stable unit treatment value assumption (SUTVA) as articulated by Rubin, each child at risk of retention has two potential outcomes: Y(1) if retained and Y(0) if promoted. But SUTVA is questionable, because a child's potential outcomes will plausibly depend on which school that child attends and also on treatment assignments of other children. We develop a c...
• Random forests and adaptive nearest neighbors AI翻译
  作者：Lin, Yi; Jeon, Yongho
  作者单位：University of Wisconsin System; University of Wisconsin Madison
  摘要：In this article we study random forests through their connection with a new framework of adaptive nearest-neighbor methods. We introduce a concept of potential nearest neighbors (k-PNNs) and show that random forests can be viewed as adaptively weighted k-PNN methods. Various aspects of random forests can be studied from this perspective. We study the effect of terminal node sizes on the prediction accuracy of random forests. We further show that random forests with adaptive splitting schemes a...
• Non-gaussian Bayesian geostatistical modeling AI翻译
  作者：Palacios, M. Blanca; Steel, Mark F. J.
  作者单位：University of Basque Country; University of Warwick
  摘要：Sampling models for geostatistical data are usually based on Gaussian processes. However, real data often display non-Gaussian features, such as heavy tails. In this article we propose a more flexible class of sampling models. We start from the spatial linear model that has a spatial trend plus a stationary Gaussian error process. We extend the sampling model to non-Gaussianity by including a scale parameter at each location. We make sure that we obtain a valid stochastic process. The scale pa...
• Large-sample joint posterior approximations when full conditionals are approximately normal: Application to generalized linear mixed models AI翻译
  作者：Su, Chun-Lung; Johnson, Wesley O.
  作者单位：University of California System; University of California Davis; University of California System; University of California Irvine
  摘要：Modern Bayesian statistical methods, such as Gibbs and Metropolis-Hastings sampling, were developed to liberate statisticians from the necessity of making large-sample assumptions and to facilitate the numerical approximation of problems that had previously been analytically intractable. Counter to this trend, we develop a method for constructing asymptotic joint posterior approximations based on models with k blocks of parameters and where the corresponding properly normalized full conditiona...
• Adaptive thresholds: Monitoring streams of network counts AI翻译
  作者：Lambert, D; Liu, CH
  摘要：This article describes a fast, statistically principled method for monitoring streams of network counts, which have long-term trends, rough cyclical patterns, outliers, and missing data. The key step is to build a reference (predictive) model for the counts that captures their complex, salient features but has just a few parameters that can be kept up-to-date as the counts flow by, without requiring access to past data. This article justifies using a negative binomial reference distribution wi...
• Focused information criteria and model averaging for the Cox hazard regression model AI翻译
  作者：Hjort, Nils Lid; Claeskens, Gerda
  作者单位：University of Oslo; Universite Catholique Louvain; Universite Catholique Louvain
  摘要：This article is concerned with variable selection methods for the Cox proportional hazards regression model. Including excessive covariates causes extra variability and inflated confidence intervals for regression parameters; thus regimes for discarding the less informative ones are needed. Our framework has p covariates designated as protected, while variables from a further set of q covariates are examined for possible inclusion or exclusion. We develop a focused information criterion (FIC) ...
• Quality control and robust estimation for cDNA microarrays with replicates AI翻译
  作者：Gottardo, R; Raftery, AE; Yeung, KY; Bumgarner, RE
  作者单位：University of British Columbia; University of Washington; University of Washington Seattle; University of Washington; University of Washington Seattle
  摘要：We consider robust estimation of gene intensities from cDNA microarray data with replicates. Several statistical methods for estimating gene intensities from microarrays have been proposed, but little work has been done on robust estimation. This is particularly relevant for experiments with replicates, because even one outlying replicate can have a disastrous effect on the estimated intensity for the gene concerned. Because of the many steps involved in the experimental process from hybridiza...
• Causal vaccine effects on binary postinfection outcomes AI翻译
  作者：Hudgens, MG; Halloran, ME
  作者单位：University of North Carolina; University of North Carolina Chapel Hill; Emory University
  摘要：The effects of vaccine on postinfection outcomes, such as disease, death, and secondary transmission to others. are important scientific and public health aspects of prophylactic vaccination. As a result, evaluation of many vaccine effects condition on being infected. Conditioning on an event that occurs posttreatment (in our case, infection subsequent to assignment to vaccine or control) can result in selection bias. Moreover, because the set of individuals who would become infected if vaccin...