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981.
This paper concerns a robust variable selection method in multiple linear regression: the robust S-nonnegative garrote variable selection method. In this paper the consistency of the method, both in terms of estimation and in terms of variable selection, is established. Moreover, the robustness properties of the method are further investigated by providing a lower bound for the breakdown point, and by deriving the influence function. The provided expressions nicely reveal the impact that the choice of an initial estimator has on the robustness properties of the variable selection method. Illustrative examples of influence functions for the S-nonnegative garrote as well as for the original (non-robust) nonnegative garrote variable selection method are provided. 相似文献
982.
We study a group lasso estimator for the multivariate linear regression model that accounts for correlated error terms. A block coordinate descent algorithm is used to compute this estimator. We perform a simulation study with categorical data and multivariate time series data, typical settings with a natural grouping among the predictor variables. Our simulation studies show the good performance of the proposed group lasso estimator compared to alternative estimators. We illustrate the method on a time series data set of gene expressions. 相似文献
983.
On the relationship between the sample size and the number of variables in a linear regression model
V.I. Oliker 《统计学通讯:理论与方法》2013,42(6):509-516
The problem of determining the number of variables to be included in the linear regression model is considered under the assumption that the dependent and independent variables have a joint normal distribution. It is shown that for a given sample size n there exists an optimal number k0 (0 ≤ k0 < n-2) of variables among all independent variables in the model, such that the expectation of the mean squared error corresponding to the prediction equation with k0 variables is minimal.Application of this result to ustepwise procedures is discussed. 相似文献
984.
985.
Diego I. Gallardo Heleno Bolfarine Atonio Carlos Pedroso-de-Lima 《Journal of applied statistics》2017,44(16):2949-2962
In this paper, the destructive negative binomial (DNB) cure rate model with a latent activation scheme [V. Cancho, D. Bandyopadhyay, F. Louzada, and B. Yiqi, The DNB cure rate model with a latent activation scheme, Statistical Methodology 13 (2013b), pp. 48–68] is extended to the case where the observations are grouped into clusters. Parameter estimation is performed based on the restricted maximum likelihood approach and on a Bayesian approach based on Dirichlet process priors. An application to a real data set related to a sealant study in a dentistry experiment is considered to illustrate the performance of the proposed model. 相似文献
986.
Niklas K. Steffens Miguel A. Fonseca Michelle K. Ryan Floor A. Rink Janka I. Stoker Anne Nederveen Pieterse 《The Leadership Quarterly》2018,29(6):637-647
In the present research we report results from two experimental studies that examine how feedback about leadership potential impacts leadership ambition, organizational commitment, and performance. Study 1 used an experimental vignette methodology that controls for prior performance. Results show that individuals who receive feedback that they have low potential to be a future leader have lower ambition and organizational commitment relative to those who receive feedback that they have high potential to be a future leader. Study 2 provides evidence of the causal behavioral effects of feedback about leadership potential using a real task effort environment. Results show that participants informed to be unlikely future leaders display lower performance in a subsequent task than participants informed to be likely future leaders. The findings from the two studies demonstrate that information about leadership potential affects subsequent ambition to become leaders as well as performance. We discuss the implications of these findings for the importance of followership, talent management, and leadership succession. 相似文献
987.
白杰 《石家庄铁道学院学报(社会科学版)》2010,4(1):94-96
近年来,关于大学英语四级与学位是否脱钩的问题出现了激烈的争论。通过对大学英语四级考试的回顾以及对出现问题的思考,并对石家庄铁道学院180名学生进行了关于英语四级与学位是否脱钩的调查。采取了实证性研究,得出结论,并就下一步的英语教学提出了相应的对策。 相似文献
988.
M. I. Rolfe K. Mengersen G. Beadle K. Vearncombe B. Andrew H. L. Johnson 《Journal of applied statistics》2010,37(5):725-738
This paper investigates the impact of chemotherapy on cognitive function of breast cancer patients and whether this response is homogeneous for all patients. Latent class piecewise linear trajectory (growth) models were employed to describe changes and identify subgroups in three Auditory Verbal Learning Test measures (learning, immediate retention and delayed recall) in 130 breast cancer patients taken at three time periods: before chemotherapy and 1 and 6 months post-chemotherapy. Two distinct subgroups of women exhibiting different patterns of response were identified for learning and delayed recall and three for immediate retention. The groups differed in level (intercept) at 1 month post-chemotherapy and patterns of decline and recovery. Binomial and multinomial logistic regressions on the latent classes found that age, initial National Adult Reading Test (NART)-predicted IQ, stage of cancer and the initial Functional Assessment of Cancer Therapy-Breast subscale (or subsets thereof) to be significant predictors of classes. 相似文献
989.
P-splines regression provides a flexible smoothing tool. In this paper we consider difference type penalties in a context
of nonparametric generalized linear models, and investigate the impact of the order of the differencing operator. Minimizing
Akaike’s information criterion we search for a possible best data-driven value of the differencing order. Theoretical derivations
are established for the normal model and provide insights into a possible ‘optimal’ choice of the differencing order and its
interrelation with other parameters. Applications of the selection procedure to non-normal models, such as Poisson models,
are given. Simulation studies investigate the performance of the selection procedure and we illustrate its use on real data
examples. 相似文献
990.
Maarten J. Nauta Arnout R. H. Fischer Esther D. Van Asselt Aarieke E. I. De Jong Lynn J. Frewer Rob De Jonge 《Risk analysis》2008,28(1):179-192
The improvement of food safety in the domestic environment requires a transdisciplinary approach, involving interaction between both the social and natural sciences. This approach is applied in a study on risks associated with Campylobacter on broiler meat. First, some web-based information interventions were designed and tested on participant motivation and intentions to cook more safely. Based on these self-reported measures, the intervention supported by the emotion "disgust" was selected as the most promising information intervention. Its effect on microbial cross-contamination was tested by recruiting a set of participants who prepared a salad with chicken breast fillet carrying a known amount of tracer bacteria. The amount of tracer that could be recovered from the salad revealed the transfer and survival of Campylobacter and was used as a measure of hygiene. This was introduced into an existing risk model on Campylobacter in the Netherlands to assess the effect of the information intervention both at the level of exposure and the level of human disease risk. We showed that the information intervention supported by the emotion "disgust" alone had no measurable effect on the health risk. However, when a behavioral cue was embedded within the instruction for the salad preparation, the risk decreased sharply. It is shown that a transdisciplinary approach, involving research on risk perception, microbiology, and risk assessment, is successful in evaluating the efficacy of an information intervention in terms of human health risks. The approach offers a novel tool for science-based risk management in the area of food safety. 相似文献