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养分吸收速率方程的非参数估计AI 解读

Knowledge of the rate of a biological process is important for characterizing the system and is necessary for gaining a deeper understanding of the process. Consider measurements, Y, made over time on a system following the model Y = f(t) + e, where f is a smooth, unknown function and e is measurement error. Although most statistical methodology has focused on estimating f(t) or f′(t), in some applications what is of real biological interest is the relationship between f and…

含随机趋势成分回归模型的最大似然估计AI 解读

This article is concerned with the estimation of a regression model with a stochastic trend component. It is shown that the probability of estimating the trend to be deterministic is very sensitive to the type of likelihood function used as the basis of inference.

删失数据中双变量生存曲线的可识别性AI 解读

We show that the survival curve is identifiable in bivariate censored data problems under weaker independence assumptions than have commonly been made. The common assumption has been mutual independence of (T 1, T 2) and (Z 1, Z 2), where (T 1, T 2) is the true survival vector, (Z 1, Z 2) is a nuisance censoring vector, and bivariate right-censored data is observed. We show that the distribution of (T 1, T 2) is identifiable under weaker, conditional independence assumptions…

稳健奇异值分解：投影寻踪的新方法AI 解读

Robust location and covariance estimators are developed via general M estimation for covariance matrix eigenvectors and eigenvalues. The solution to this GM estimation problem is obtained by transforming it into a series of robust regression problems based on a new algorithm for the singular value decomposition. It is shown here that the singular value decomposition can be represented as an iteration of two steps: a least squares regression fit of the data matrix followed by…

模拟极端次序统计量的半参数自助法AI 解读

We propose a technique for simulating the joint distribution of the j largest order statistics of a very large sample. We assume that the parent population is in the domain of attraction of the Type 1 (Gumbel) extreme value distribution. The bootstrap variates are generated by resampling the normalized spacings of the k largest observed values in the original data where k is larger than j. We compare the bootstrap distribution to the fitted extremal distribution of Weissman.…

化疗克隆形成试验的实验设计AI 解读

One approach to estimating the number of cells with high growth potential in a cancer patient is the assessment of tumor cell colony formation in semisolid medium. A potential indicator of the clinical response to a specific drug is the capacity of the drug to reduce the formation of cell colonies. Often, a Poisson log-linear model provides an adequate representation of the dose-response curve. This model is then summarized by the dose required to reduce the number of…

摘要暂缺

统计理论与建模：纪念 David Cox 爵士AI 解读

Part 1 Statistical theory - theoretical concepts significance tests theory of optimal tests estimation asymptotic theory. Part 2 Applied statistics - preliminary considerations statistical models statistical inference model adequancy exploratory and robust methods multi-variate methods use of computers. Part 3 Generalized linear models - a class of non-linear regression models likelihood functions estimation analysis of deviance checking the model. Part 4 Residuals and…

摘要暂缺

变量选择问题中的观测影响评估AI 解读

Variable selection techniques are often used in combination with multiple linear regression to produce a parsimonious model that fits the data well.It is clearly undesirable for the final model to depend strongly on the inclusion of a few influential cases (data points) in the data set.This article discusses a measure of influence of single cases on the final model, based on a similar measure used in ordinary multiple regression.When variables are selected objectively using…

物种数量估计：综述AI 解读

How many kinds are there? Suppose that a population is partitioned into C classes. In many situations interest focuses not on estimation of the relative sizes of the classes, but on estimation of C itself. For example, biologists and ecologists may be interested in estimating the number of species in a population of plants or animals, numismatists may be concemed with estimating the number of dies used to produce an ancient coin issue, and linguists may be interested in…

序贯概率预测有效性的检验AI 解读

Events are observed sequentially, and at each stage a probability for the next event is assessed. We consider the relationship between the sequence of probability forecasts and the sequence of outcomes. We argue that the forecasts may be considered “empirically valid” when both these sequences are consistent with a common joint distribution for the events. To aid in assessing validity, we introduce various test statistics that measure, in a natural way, the empirical…

具有非单调依赖结构的二元分布AI 解读

A new ordering for nonmonotone dependence is proposed, and a method is presented for describing parametric families of bivariate distributions with fixed marginals and specified dependence structures. The method is easy to use and allows for arbitrary marginals and arbitrary dependence structures (e.g., structures of nonmonotone dependence). Any parametric family of bivariate distributions is ordered by the nonmonotone dependence ordering constructed from the desirable…

Gibbs 采样器的渐近行为AI 解读

Mild sufficient conditions for the ergodicity of the Gibbs sampler are obtained. The geometric ergodicity of the Gibbs sampler is then discussed, where the main tool is the “drift” criterion. This criterion requires the construction of a generalized energy function so that the chain is dissipating energy, at a suitable rate, whenever it lies outside the “center” of the state-space. For the “two-variable” case, a useful recipe is provided for constructing appropriate energy…

利用非参数校准进行有限总体偏差稳健估计AI 解读

A Standard problem in sample survey inference is that of predicting the finite population total H of a function h(y) of a random variable Y. The model-based approach to this problem first defines a working model ξ for Y and then predicts H by estimating its expectation under ξ, conditional on the sample values of Y. This approach leads to biased predictions if ξ is incorrect. We explore an automatic solution to this misspecification bias that uses nonparametric regression to…

稳健估计、非正态性与广义指数分布AI 解读

The detection and treatment of outliers in data has represented an important area of research. The general approach that has been adopted involves observing that outliers contribute to the “fatness” in the tails of the error distribution and using an appropriate model of the error term to take this into account. This article introduces a general dass of distributions to capture nonnormalities in the data based on the generalized exponential family. This family of…

基于数据深度的质量指数与多元秩检验AI 解读

Let F and G be the distribution functions of two given populations on Rp, p ≥ 1. We introduce and study a Parameter Q = Q(F, G), which measures the Overall “outlyingness” of population G relative to population F. The Parameter Q can be defined using any concept of data depth. Its value ranges from 0 to 1, and is .5 when F and G are identical. We show that within the dass of elliptical distributions when G departs from F in location or G has a larger spread, or both, the…

利用共轭梯度加速 EM 算法AI 解读

The EM algorithm is a very popular and widely applicable algorithm for the computation of maximum likelihood estimates. Although its implementation is generally simple, the EM algorithm often exhibits slow convergence and is costly in some areas of application. Past attempts to accelerate the EM algorithm have most commonly been based on some form of Aitken acceleration. Here we propose an alternative method based on conjugate gradients. The key, as we show, is that the EM…

利用暴露概率信息推断暴露与疾病的关联AI 解读

Unconditional and conditional likelihood methods are proposed for modeling odds and odds ratios relating a binary disease variable and an exposure variable that is only known probabilistically (e.g., via measurement of a Surrogate exposure variable), while adjusting appropriately for a vector of covariables. Assuming nondifferential errors, a probabilistic structure is developed that permits analysis of the marginal relation between disease and the Surrogate while…

协变量存在测量误差的病例对照研究AI 解读

We devise methods for estimating the parameters of a prospective logistic model with dichotomous response D and arbitrary covariates X from case-control data when these covariates are measured with error. We suppose that some fraction of the cases and controls provide only the error-prone covariate measurements, W (the “incomplete” or “reduced” data), whereas some of the cases and controls provide measurements on X and W (the “complete” data). We assume a measurement error…

摘要暂缺

广义线性模型中的随机效应预测AI 解读

This article develops an estimating function-based approach to component estimation in the two-stage generalized linear model with univariate random effects and a vector of fixed effects. The novelty and unifying feature of the method is the use of estimating functions in the estimation of both the random effects and their variance. Two separate estimating procedures based on the method are proposed that differ in the intensity of numerical computation required. The…

分离假设检验与自适应检验统计量的 Bahadur 效率AI 解读

The notion of separability of hypotheses was first introduced by Cox (1961); two families of hypotheses are separate if no distribution in one family can be obtained as a limit of distributions from the other family. For testing separate hypotheses, Cox (1961, 1962) suggested the test based on the comparison of the logarithm of the likelihood ratio with its expected value (or estimate thereof) under each hypothesis. The tests of such hypotheses are required to have high…

删失生存数据中有序备择假设的检验AI 解读

In animal carcinogenesis experiments or comparative clinical trials where the r groups correspond to increasing dosages of an agent or an increasing number of additional modalities and the primary outcome is time to a certain event (e.g., tumor occurrence, death) T, ordered alternatives of the form H1 : S1 ≤ S2 ≤ · · · ≤ Sr , where Si(t) = Pr (Ti > t) is the survival function for group are of special interest. Using the counting process formulation of the problem and…