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A discrete truncated Zipf distribution 一个离散的截断Zipf分布
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-09-26 DOI: 10.1111/stan.12280
Kwame Boamah-Addo, T. Kozubowski, A. Panorska
We provide a comprehensive account of fundamental properties of a truncated discrete Zipf distribution, complementing the results available in the literature. In particular, we obtain results on existence and uniqueness of maximum likelihood parameter estimators and propose new testing methodology for the shape parameter. We also include data examples illustrating applicability of this stochastic model.
我们提供了截断离散Zipf分布的基本性质的全面说明,补充了文献中可用的结果。特别地,我们得到了极大似然参数估计的存在唯一性的结果,并提出了形状参数的新的检验方法。我们还提供了数据示例来说明该随机模型的适用性。
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引用次数: 0
Rank correlation inferences for clustered data with small sample size. 小样本量聚类数据的秩相关推断。
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-08-01 Epub Date: 2022-01-12 DOI: 10.1111/stan.12261
Sally Hunsberger, Lori Long, Sarah E Reese, Gloria H Hong, Ian A Myles, Christa S Zerbe, Pleonchan Chetchotisakd, Joanna H Shih

This paper develops methods to test for associations between two variables with clustered data using a U-Statistic approach with a second-order approximation to the variance of the parameter estimate for the test statistic. The tests that are presented are for clustered versions of: Pearsons χ 2 test, the Spearman rank correlation and Kendall's τ for continuous data or ordinal data and for alternative measures of Kendall's τ that allow for ties in the data. Shih and Fay use the U-Statistic approach but only consider a first-order approximation. The first-order approximation has inflated significance level in scenarios with small sample sizes. We derive the test statistics using the second-order approximations aiming to improve the type I error rates. The method applies to data where clusters have the same number of measurements for each variable or where one of the variables may be measured once per cluster while the other variable may be measured multiple times. We evaluate the performance of the test statistics through simulation with small sample sizes. The methods are all available in the R package cluscor.

本文开发的方法,以检验两个变量之间的关联与聚类数据使用u -统计方法与二阶近似的方差估计参数的检验统计量。所提供的检验是针对以下聚类版本的检验:连续数据或有序数据的皮尔逊χ 2检验、斯皮尔曼等级相关性和肯德尔τ,以及允许数据中存在联系的肯德尔τ的替代度量。Shih和Fay使用u统计方法,但只考虑一阶近似。在小样本量的情况下,一阶近似具有膨胀的显著性水平。我们使用二阶近似来推导测试统计量,旨在提高I型错误率。该方法适用于集群对每个变量具有相同数量的测量的数据,或者其中一个变量可能每个集群测量一次,而另一个变量可能被测量多次的数据。我们通过小样本量的模拟来评估测试统计量的性能。这些方法都可以在R包分类中获得。
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引用次数: 0
Testing for differences in chain equating 检验链等式的差异
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-07-22 DOI: 10.1111/stan.12277
Michela Battauz
The comparability of the scores obtained in different forms of a test is certainly an essential requirement. This paper proposes a statistical test for the detection of noncomparable scores based on item response theory (IRT) methods. When the IRT model is fit separately for different forms of a test, the item parameter estimates are expressed on different measurement scales. The first step to obtain comparable scores is to convert the item parameters to a common metric using two constants, called equating coefficients. The equating coefficients can be estimated for two forms with common items, or derived through a chain of forms. The proposal of this paper is a statistical test to verify whether the scale conversions provided by the equating coefficients are as expected when the assumptions of the model are satisfied, hence leading to comparable scores. The method is illustrated through simulation studies and a real‐data example.
在不同形式的考试中获得的分数的可比性当然是一项基本要求。本文提出了一种基于项目反应理论(IRT)方法的非可比分数检测的统计检验方法。当对不同形式的测试分别拟合IRT模型时,项目参数估计在不同的测量尺度上表示。获得可比分数的第一步是使用两个常量(称为相等系数)将项目参数转换为公共度量。相等系数可以用共同项估计两种形式,或通过一系列形式推导。本文的提议是一个统计检验,验证在满足模型假设的情况下,等式系数提供的尺度转换是否如预期的那样,从而得到可比较的分数。通过仿真研究和一个实际数据实例说明了该方法。
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引用次数: 1
Usual stochastic ordering of the sample maxima from dependent distribution‐free random variables 从非相关分布随机变量得到的样本最大值的通常随机排序
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-07-21 DOI: 10.1111/stan.12275
Longxiang Fang, N. Balakrishnan, Wenyu Huang, Shuai Zhang
In this paper, we discuss stochastic comparison of the largest order statistics arising from two sets of dependent distribution‐free random variables with respect to multivariate chain majorization, where the dependency structure can be defined by Archimedean copulas. When a distribution‐free model with possibly two parameter vectors has its matrix of parameters changing to another matrix of parameters in a certain mathematical sense, we obtain the first sample maxima is larger than the second sample maxima with respect to the usual stochastic order, based on certain conditions. Applications of our results for scale proportional reverse hazards model, exponentiated gamma distribution, Gompertz–Makeham distribution, and location‐scale model, are also given. Meanwhile, we provide two numerical examples to illustrate the results established here.
本文讨论了由两组无相关分布的随机变量引起的最大阶统计量的随机比较,其中相关结构可由阿基米德copuls定义。当一个可能有两个参数向量的无分布模型的参数矩阵在一定的数学意义上改变为另一个参数矩阵时,我们得到了基于通常随机顺序的第一个样本最大值大于第二个样本最大值,基于某些条件。我们的结果在比例逆向灾害模型、指数伽马分布、Gompertz-Makeham分布和位置尺度模型中的应用也被给出。同时,给出了两个数值算例来说明本文的结论。
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引用次数: 0
Inverse‐probability‐weighted logrank test for stratified survival data with missing measurements 缺失测量的分层生存数据的逆概率加权logrank检验
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-07-21 DOI: 10.1111/stan.12276
Rim Ben Elouefi, Foued Saâdaoui
The stratified logrank test can be used to compare survival distributions of several groups of patients, while adjusting for the effect of some discrete variable that may be predictive of the survival outcome. In practice, it can happen that this discrete variable is missing for some patients. An inverse‐probability‐weighted version of the stratified logrank statistic is introduced to tackle this issue. Its asymptotic distribution is derived under the null hypothesis of equality of the survival distributions. A simulation study is conducted to assess behavior of the proposed test statistic in finite samples. An analysis of a medical dataset illustrates the methodology.
分层logrank检验可用于比较几组患者的生存分布,同时调整一些可能预测生存结果的离散变量的影响。在实践中,这一离散变量对某些患者来说可能是缺失的。引入了分层logrank统计的逆概率加权版本来解决这个问题。在生存分布相等的零假设下,导出了其渐近分布。通过仿真研究来评估所提出的检验统计量在有限样本中的行为。对医学数据集的分析说明了这种方法。
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引用次数: 0
Assessing replicability with the sceptical p$$ p $$ ‐value: Type‐I error control and sample size planning 用怀疑p $$ p $$值评估可复制性:I型误差控制和样本量计划
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-07-01 DOI: 10.1111/stan.12312
Charlotte Micheloud, F. Balabdaoui, L. Held
We study a statistical framework for replicability based on a recently proposed quantitative measure of replication success, the sceptical p$$ p $$ ‐value. A recalibration is proposed to obtain exact overall Type‐I error control if the effect is null in both studies and additional bounds on the partial and conditional Type‐I error rate, which represent the case where only one study has a null effect. The approach avoids the double dichotomization for significance of the two‐trials rule and has larger project power to detect existing effects over both studies in combination. It can also be used for power calculations and requires a smaller replication sample size than the two‐trials rule for already convincing original studies. We illustrate the performance of the proposed methodology in an application to data from the Experimental Economics Replication Project.
我们研究了一个统计框架的可复制性基于最近提出的复制成功的定量测量,怀疑p $$ p $$‐值。如果两项研究的影响为零,以及部分和条件型I错误率的附加界限,则建议重新校准以获得精确的总体型I误差控制,这代表了只有一项研究具有零效应的情况。该方法避免了两次试验规则显著性的双重二分法,并且具有更大的项目能力来检测两项研究合并后的现有效应。它也可以用于功率计算,并且需要比已经令人信服的原始研究的两次试验规则更小的复制样本量。我们在实验经济学复制项目的数据应用中说明了所提出方法的性能。
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引用次数: 3
Automatic bias correction for testing in high‐dimensional linear models 用于高维线性模型测试的自动偏差校正
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-07-01 DOI: 10.1111/stan.12274
Jing Zhou, G. Claeskens
Hypothesis testing is challenging due to the test statistic's complicated asymptotic distribution when it is based on a regularized estimator in high dimensions. We propose a robust testing framework for ℓ1$$ {ell}_1 $$ ‐regularized M‐estimators to cope with non‐Gaussian distributed regression errors, using the robust approximate message passing algorithm. The proposed framework enjoys an automatically built‐in bias correction and is applicable with general convex nondifferentiable loss functions which also allows inference when the focus is a conditional quantile instead of the mean of the response. The estimator compares numerically well with the debiased and desparsified approaches while using the least squares loss function. The use of the Huber loss function demonstrates that the proposed construction provides stable confidence intervals under different regression error distributions.
假设检验是基于高维正则化估计量的,由于检验统计量的渐近分布复杂,所以假设检验具有挑战性。利用鲁棒近似消息传递算法,提出了一种用于处理非高斯分布回归误差的1 $$ {ell}_1 $$正则化M估计的鲁棒测试框架。所提出的框架具有自动内置的偏差校正功能,适用于一般凸不可微损失函数,当焦点是条件分位而不是响应的平均值时,也允许进行推理。当使用最小二乘损失函数时,该估计方法与去偏和去杂化方法在数值上有很好的比较。Huber损失函数的使用表明,所提出的构造在不同的回归误差分布下提供了稳定的置信区间。
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引用次数: 0
Assessing skewness in financial markets 评估金融市场的偏差
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-05-30 DOI: 10.1111/stan.12273
Giovanni Campisi, L. La Rocca, S. Muzzioli
It is a matter of common observation that investors value substantial gains but are averse to heavy losses. Obvious as it may sound, this translates into an interesting preference for right‐skewed return distributions, whose right tails are heavier than their left tails. Skewness is thus not only a way to describe the shape of a distribution, but also a tool for risk measurement. We review the statistical literature on skewness and provide a comprehensive framework for its assessment. Then, we present a new measure of skewness, based on the decomposition of variance in its upward and downward components. We argue that this measure fills a gap in the literature and show in a simulation study that it strikes a good balance between robustness and sensitivity.
投资者看重可观的收益,但不愿遭受重大损失,这是一个普遍的观察结果。虽然听起来很明显,但这转化为对右倾斜的回报分布的有趣偏好,其右尾比左尾重。因此,偏度不仅是描述分布形状的一种方式,也是衡量风险的一种工具。我们回顾了关于偏度的统计文献,并为其评估提供了一个全面的框架。然后,我们提出了一种新的测量偏度,基于方差的分解在其上下分量。我们认为这一措施填补了文献中的空白,并在模拟研究中表明,它在鲁棒性和敏感性之间取得了很好的平衡。
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引用次数: 0
Autoregressive and moving average models for zero‐inflated count time series 零膨胀计数时间序列的自回归和移动平均模型
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-05-01 DOI: 10.1111/stan.12255
Vurukonda Sathish, S. Mukhopadhyay, R. Tiwari
Zero inflation is a common nuisance while monitoring disease progression over time. This article proposes a new observation‐driven model for zero‐inflated and over‐dispersed count time series. The counts given from the past history of the process and available information on covariates are assumed to be distributed as a mixture of a Poisson distribution and a distribution degenerated at zero, with a time‐dependent mixing probability, πt . Since, count data usually suffers from overdispersion, a Gamma distribution is used to model the excess variation, resulting in a zero‐inflated negative binomial regression model with mean parameter λt . Linear predictors with autoregressive and moving average (ARMA) type terms, covariates, seasonality and trend are fitted to λt and πt through canonical link generalized linear models. Estimation is done using maximum likelihood aided by iterative algorithms, such as Newton‐Raphson (NR) and Expectation and Maximization. Theoretical results on the consistency and asymptotic normality of the estimators are given. The proposed model is illustrated using in‐depth simulation studies and two disease datasets.
随着时间的推移监测疾病进展时,零通胀是一个常见的麻烦。本文提出了一个新的观测驱动模型,用于零膨胀和过分散计数时间序列。从过去的过程历史中给出的计数和有关协变量的可用信息被假设为泊松分布和在零处退化的分布的混合分布,具有时间相关的混合概率πt。由于计数数据通常存在过度分散,因此使用Gamma分布来模拟过度变化,从而产生具有平均参数λt的零膨胀负二项回归模型。通过正则链接广义线性模型拟合具有自回归和移动平均(ARMA)型项、协变量、季节性和趋势的线性预测因子λt和πt。估计是在迭代算法(如Newton - Raphson (NR)和Expectation and Maximization)的辅助下使用最大似然来完成的。给出了估计量的相合性和渐近正态性的理论结果。所提出的模型使用深度模拟研究和两个疾病数据集来说明。
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引用次数: 1
Threshold estimation for continuous three‐phase polynomial regression models with constant mean in the middle regime 中区均值为常数的连续三相多项式回归模型的阈值估计
IF 1.5 3区 数学 Q2 Mathematics Pub Date : 2022-04-21 DOI: 10.1111/stan.12268
Chih‐Hao Chang, Kam-Fai Wong, Wei‐Yee Lim
This paper considers a continuous three‐phase polynomial regression model with two threshold points for dependent data with heteroscedasticity. We assume the model is polynomial of order zero in the middle regime, and is polynomial of higher orders elsewhere. We denote this model by ℳ2$$ {mathcal{M}}_2 $$ , which includes models with one or no threshold points, denoted by ℳ1$$ {mathcal{M}}_1 $$ and ℳ0$$ {mathcal{M}}_0 $$ , respectively, as special cases. We provide an ordered iterative least squares (OiLS) method when estimating ℳ2$$ {mathcal{M}}_2 $$ and establish the consistency of the OiLS estimators under mild conditions. When the underlying model is ℳ1$$ {mathcal{M}}_1 $$ and is (d0−1)$$ left({d}_0-1right) $$ th‐order differentiable but not d0$$ {d}_0 $$ th‐order differentiable at the threshold point, we further show the Op(N−1/(d0+2))$$ {O}_pleft({N}^{-1/left({d}_0+2right)}right) $$ convergence rate of the OiLS estimators, which can be faster than the Op(N−1/(2d0))$$ {O}_pleft({N}^{-1/left(2{d}_0right)}right) $$ convergence rate given in Feder when d0≥3$$ {d}_0ge 3 $$ . We also apply a model‐selection procedure for selecting ℳκ$$ {mathcal{M}}_{kappa } $$ ; κ=0,1,2$$ kappa =0,1,2 $$ . When the underlying model exists, we establish the selection consistency under the aforementioned conditions. Finally, we conduct simulation experiments to demonstrate the finite‐sample performance of our asymptotic results.
本文考虑具有异方差的相关数据具有两个阈值点的连续三相多项式回归模型。我们假设模型在中间区域是零阶多项式,在其他区域是高阶多项式。我们将该模型表示为$$ {mathcal{M}}_2 $$ ,其中包括有或没有阈值点的模型,用ta1表示$$ {mathcal{M}}_1 $$ 和:0$$ {mathcal{M}}_0 $$ ,分别作为特殊情况。我们提供了一种有序迭代最小二乘(OiLS)方法来估计1$$ {mathcal{M}}_2 $$ 并建立了温和条件下油液估测器的一致性。当底层模型为$$ {mathcal{M}}_1 $$ 是(d0−1)$$ left({d}_0-1right) $$ 阶可微但不是0$$ {d}_0 $$ 在阈值点处,我们进一步证明了Op(N−1/(d0+2))$$ {O}_pleft({N}^{-1/left({d}_0+2right)}right) $$ oil估计器的收敛速度比Op(N−1/(2d0))更快。$$ {O}_pleft({N}^{-1/left(2{d}_0right)}right) $$ 当d0≥3时,Feder给出的收敛速度$$ {d}_0ge 3 $$ . 我们还应用模型选择程序来选择κ$$ {mathcal{M}}_{kappa } $$ ;κ=0,1,2$$ kappa =0,1,2 $$ . 当底层模型存在时,我们建立了上述条件下的选择一致性。最后,我们进行了模拟实验来证明我们的渐近结果的有限样本性能。
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引用次数: 0
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Statistica Neerlandica
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