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1.
In the area of quality of life research, researchers may ask respondents to rate importance as well as satisfaction of various life domains (such as job and health) and use importance ratings as weights to calculate overall, or global, life satisfaction. The practice of giving more important domains more weight, known as importance weighting, has not been without controversy. Several previous studies assessed importance weighting using the analytical approach of moderated regression. This study discusses major issues related to how importance weighting has been assessed. Specifically, this study highlights that studies on importance weighting without considering statistical power are prone to type II error, i.e., failing to reject the null hypothesis of no significant weighting effect when the null hypothesis is actually false. The sample size required for adequate statistical power to detect importance weighting functions appeared larger than most previous studies could offer. 相似文献
2.
Nuttanan Wichitaksorn 《统计学通讯:理论与方法》2020,49(8):1801-1817
AbstractThis article proposes a new approach to analyze multiple vector autoregressive (VAR) models that render us a newly constructed matrix autoregressive (MtAR) model based on a matrix-variate normal distribution with two covariance matrices. The MtAR is a generalization of VAR models where the two covariance matrices allow the extension of MtAR to a structural MtAR analysis. The proposed MtAR can also incorporate different lag orders across VAR systems that provide more flexibility to the model. The estimation results from a simulation study and an empirical study on macroeconomic application show favorable performance of our proposed models and method. 相似文献
4.
Sets of relatively short time series arise in many situations. One aspect of their analysis may be the detection of outlying
series. We examine the performance of standard normal outlier tests applied to the means, or to simple functions of the means,
of AR(1) series, not necessarily of equal lengths. Although unequal lengths of series implies that the means have unequal
variances, that are only known approximately, it is shown that nominal significance levels hold good under most circumstances.
Thus a standard outlier test can usefully be applied, avoiding the complication of estimating the time series' parameters.
The test's power is affected by unequal lengths, being higher when the slippage occurs in one of the longer series 相似文献
5.
Distributions generated by perturbation of symmetry with emphasis on a multivariate skew t-distribution 总被引:1,自引:0,他引:1
Adelchi Azzalini Antonella Capitanio 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2003,65(2):367-389
Summary . A fairly general procedure is studied to perturb a multivariate density satisfying a weak form of multivariate symmetry, and to generate a whole set of non-symmetric densities. The approach is sufficiently general to encompass some recent proposals in the literature, variously related to the skew normal distribution. The special case of skew elliptical densities is examined in detail, establishing connections with existing similar work. The final part of the paper specializes further to a form of multivariate skew t -density. Likelihood inference for this distribution is examined, and it is illustrated with numerical examples. 相似文献
6.
Summary:
The H–family of distributions or H–distributions, introduced by Tukey (1960; 1977), are
generated by a single transformation of the standard normal distribution and allow for leptokurtosis
represented by the parameter h. Alternatively, Haynes et al. (1997) generated leptokurtic distributions
by applying the K–transformation to the normal distribution. In this study we propose a third transformation,
the so–called J–transformation, and derive some properties of this transformation. Moreover,
so-called elongation generating functions (EGFs) are introduced. By means of EGFs we are able to
visualize the strength of tail elongation and to construct new transformations. Finally, we compare the
three transformations towards their goodness–of–fit in the context of financial return data. 相似文献
7.
The robustness of Mauchly's sphericity test criterion when sampling from a mixture of two multivariate normal distributions is studied. The distribution of the sphericity test criterion when the sample covariance matrix has a non-central Wishart density of rank one is derived in terms of Meijer's G-functions; its distribution under the mixture model is then deduced. The robustness is studied by computing actual significance levels of the test under the mixture model using the critical values under the usual normal model. 相似文献
8.
Stuart Barber Guy P. Nason 《Journal of the Royal Statistical Society. Series B, Statistical methodology》2004,66(4):927-939
Summary. Wavelet shrinkage is an effective nonparametric regression technique, especially when the underlying curve has irregular features such as spikes or discontinuities. The basic idea is simple: take the discrete wavelet transform of data consisting of a signal corrupted by noise; shrink or remove the wavelet coefficients to remove the noise; then invert the discrete wavelet transform to form an estimate of the true underlying curve. Various researchers have proposed increasingly sophisticated methods of doing this by using real-valued wavelets. Complex-valued wavelets exist but are rarely used. We propose two new complex-valued wavelet shrinkage techniques: one based on multiwavelet style shrinkage and the other using Bayesian methods. Extensive simulations show that our methods almost always give significantly more accurate estimates than methods based on real-valued wavelets. Further, our multiwavelet style shrinkage method is both simpler and dramatically faster than its competitors. To understand the excellent performance of this method we present a new risk bound on its hard thresholded coefficients. 相似文献
9.
康学伟 《吉林师范大学学报》2004,32(6):14-19
本文从分析吉林师范大学的发展定位与学科建设等具体问题入手,对有关教师教育和普通高师院校发展趋势、前景等一系列重要理论与实践问题进行了探讨.尽快提高办学水平是适应教师教育的迫切需要,准确定位是确定学校发展战略的前提,学科建设是提高办学水平的中心环节,调整优化学科专业结构是学科建设的主要途径. 相似文献
10.
董百志 《绍兴文理学院学报》1992,(5)
1990年R.Biswas在[2]中提出了反Fuzzy子群的概念.在此基础上本文相应定义了反Fuzzy子群的直积.接着讨论了其包括正规、共轭情况下的若干性质.此外,还给出了直积μ_1×μ_2是G×G上的反Fuzzy子群的一个充要条件. 相似文献