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作者：Chen, Baojiang; Li, Pengfei; Qin, Jing; Yu, Tao
作者单位：University of Nebraska System; University of Nebraska Medical Center
摘要：With the advent of new technology, new biomarker studies have become essential in cancer research. To achieve optimal sensitivity and specificity, one needs to combine different diagnostic tests. The celebrated Neyman Pearson lemma enables us to use the density ratio to optimally combine different diagnostic tests. In this article, we propose a semiparametric model by directly modeling, the density ratio between the diseased and nondiseased population as an unspecified monotonic nondecreasing ...
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作者：Noufaily, Angela; Farrington, Paddy; Garthwaite, Paul; Enki, Doyo Gragn; Andrews, Nick; Charlett, Andre
作者单位：University of Warwick
摘要：Many statistical surveillance systems for the timely detection of outbreaks of infectious disease operate on laboratory data. Such data typically incur reporting delays between the time at which a specimen is collected for diagnostic purposes, and the time at which the results of the laboratory analysis become available. Statistical surveillance systems currently in use usually make some ad hoc adjustment for such delays, or use counts by time of report. We propose a new statistical approach t...
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作者：Yu, Zhe; Prado, Raquel; Quinlan, Erin Burke; Cramer, Steven C.; Ombao, Hernando
作者单位：University of California System; University of California Santa Cruz
摘要：Stroke is a disturbance in blood supply to the brain resulting in the loss of brain functions, particularly motor function. A study was conducted by the UCI Neurorehabilitation Lab to investigate the impact of stroke on motor-related brain regions. Functional MRI (fMRI) data were collected from stroke patients and healthy controls while the subjects performed a simple motor task. In addition to affecting local neuronal activation strength, stroke might also alter communications (i.e., connecti...
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作者：Liu, Wei; Zhang, Zhiwei; Schroeder, R. Jason; Ho, Martin; Zhang, Bo; Long, Cynthia; Zhang, Hui; Irony, Telba Z.
作者单位：US Food & Drug Administration (FDA)
摘要：In some therapeutic areas, treatment evaluation is frequently complicated by a possible placebo effect (i.e., the psychobiological effect of a patient's knowledge or belief of being treated). When a substantial placebo effect is likely to exist, it is important to distinguish the treatment and placebo effects in quantifying the clinical benefit of a new treatment. These causal effects can be formally defined in a joint causal model that includes treatment (e.g., new vs. placebo) and treatmenta...
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作者：Yu, Zhou; Dong, Yuexiao; Zhu, Li-Xing
作者单位：Beijing Normal University; Hong Kong Baptist University
摘要：We propose trace pursuit for model-free variable selection under the sufficient dimension-reduction paradigm. Two distinct algorithms are proposed: stepwise trace pursuit and forward trace pursuit. Stepwise trace pursuit achieves selection consistency with fixed p. Forward trace pursuit can serve as an initial screening step to speed up the computation in the case of ultrahigh dimensionality. The screening, consistency property of forward trace pursuit based on sliced inverse regression is est...
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作者：Robbins, Michael W.; Gallagher, Colin M.; Lund, Robert B.
作者单位：RAND Corporation
摘要：This article develops a test for a single changepoint in a general setting that allows for correlated time series regression errors, a seasonal cycle, time-varying regression factors, and covariate information. Within, a changepoint statistic is constructed from likelihood ratio principles and its asymptotic distribution is derived. The asymptotic distribution of the changepoint statistic is shown to be invariant of the seasonal cycle and the covariates should the latter obey some simple limit...
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作者：Yan, Ying; Yi, Grace Y.
作者单位：University of Waterloo
摘要：Covariate measurement error has attracted extensive interest in survival analysis. Since Prentice, a large number of inference methods have been developed to handle error-prone data that are modulated with proportional hazards models. In contrast to proportional hazards models, additive hazards models offer a flexible tool to delineate survival processes. However, there is little research on measurement error effects under additive hazards models. In this article, we systematically investigate...
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作者：Forastiere, Laura; Mealli, Fabrizia; VanderWeele, Tyler J.
作者单位：University of Florence
摘要：Exploration of causal mechanisms is often important for researchers and policymakers to understand how an intervention works and how it can be improved. This task can be crucial in clustered encouragement designs (CEDs). Encouragement design studies arise frequently when the treatment cannot be enforced because of ethical or practical constraints and an encouragement intervention (information campaigns, incentives, etc.) is conceived with the purpose of increasing the uptake of the treatment o...
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作者：Goos, Peter; Jones, Bradley; Syafitri, Utami
作者单位：KU Leuven
摘要：In mixture experiments, the factors under study are proportions of the-ingredients-of a mixture. The special nature of the factors necessitates specific types of regression models, and specific types of experimental designs. Although mixture experiments usually are intended to predict the response(s) for all possible formulations of the mixture and to identify optimal proportions for each of the ingredients, little research has been done concerning their I-optimal design. This is surprising gi...
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作者：He, Shuyuan; Liang, Wei; Shen, Junshan; Yang, Grace
作者单位：Capital Normal University; Xiamen University; Peking University; University System of Maryland; University of Maryland College Park
摘要：When the empirical likelihood (EL) of a parameter theta is constructed with right censored data, literature shows that 2 log(empirical likelihood ratio) typically has an asymptotic scaled chi-squared distribution, where the scale parameter is a function of some unknown asymptotic variances. Therefore, the EL construction of confidence intervals for theta requires an additional estimation of the scale parameter. Additional estimation would reduce the coverage accuracy for theta. By using a spec...
