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如何选择合适的试验设计类型(五) 总被引:1,自引:0,他引:1
当试验中涉及两个因素时,若两因素之间不存在交互作用或交互作用对观测结果的影响无统计学意义,并且,特定试验条件(通常为各因素不同水平的一种组合)下试验数据的测定误差在专业上允许的范围之内,此时,可以选用"随机区组设计、平衡不完全随机区组设计、具有一个重复测量的单因素设计、无重复试验双因素设计和两因素嵌套设计"五种设计之一.在上一期讲座中,我们向读者重点介绍无重复试验双因素设计和两因素嵌套设计这两种设计类型,重点阐述了两设计类型的定义、形式、特点、应用场合以及具体实施,并用实例加以论证.试验中所涉及到的两个因素都是试验因素,仅当有预试验表明两个试验因素之间的交互作用无统计学意义,且相同试验条件下定量观测指标的取值离散度很小时,此时,可采用无重复试验双因素设计;试验因素对观测结果的影响有主次之分,或者试验因素之间存在自然属性上的嵌套关系,上层因素对观测结果的影响大于下层因素时,采用两因素嵌套设计较为适宜. 相似文献
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当试验中涉及两个因素时,若两因素之间不存在交互作用或交互作用对观测结果的影响无统计学意义,并且,特定试验条件(通常为各因素不同水平的一种组合)下试验数据的测定误差在专业上允许的范围之内,此时,可以选用“随机区组设计、平衡不完全随机区组设计、具有一个重复测量的单因素设计、无重复试验双因素设计和两因素嵌套设计”五种设计之一。在上一期讲座中,我们向读者重点介绍了随机区组设计、具有一个重复测量的单因素设计这两种设计类型,重点阐述了两设计类型的定义、形式、特点、应用场合以及具体实施,并用实例加以论证。 相似文献
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本文旨在介绍两种多因素试验设计方法,即正交设计与均匀设计。由于析因设计中的试验点数目过多,在既要较少试验点数目,又要能比较准确地揭示多因素对评价指标影响规律的要求之下,宜选择正交设计或均匀设计。正交设计具有"试验点均匀分散、整齐可比且可以事先安排少数交互作用项"的特点,因此,结果的可信度较高,只需采用方差分析处理定量资料;均匀设计具有"试验点极其均匀分散、正交性在一定程度上受到破坏,不能事先安排交互作用项"的特点,因此,允许很少数目的试验点,但需采用多重回归分析处理资料且分析结果不唯一。 相似文献
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本文目的是介绍一种可以考察各级交互作用的多因素设计类型,即析因设计。通过介绍两个实际例子,总结出析因设计的八个特点及优点、缺点。针对实际应用时可能面临的情况或问题,人们可能会对析因设计进行改造,由此产生了析因设计的三种变形,即"含区组因素的析因设计""分式析因设计"和"多因素非平衡组合试验"。最后一种情形,是实际工作者常会使用的,但在对定量评价指标进行差异性分析时需要对原先的分组进行合理拆分,再进行恰当的组合,构造出多种标准的设计类型,以利于分析者选择正确的统计分析方法。 相似文献
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当试验中涉及一个试验因素和两个区组因素时,若因素之间不存在交互作用或交互作用对观测结果的影响无统计学意义,并且,特定试验条件(通常为各因素不同水平的一种组合)下试验数据的测定误差在专业上允许的范围之内,此时,根据试验因素的水平数目多少,可以考虑选用“交叉设计或拉丁方设计”两种设计之一。在上一期讲座中,我们向读者介绍了三阶段交叉设计和3×3交叉设计这两种设计类型,重点阐述了两种设计类型的定义、形式、特点、应用场合以及具体实施,并用实例加以论证。 相似文献
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Design of a neural-net-based regulator for nonlinear plants is considered. Both state and output feedback regulators with deterministic and stochastic disturbances have been investigated. A Multilayered Feedforward Neural Network (MFNN) has been employed as the nonlinear controller. The training of the MFNN utilizes the recently developed concept of Block Partial Derivatives (BPDs). 相似文献
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Elliott R 《Psychotherapy research》2002,12(1):1-21
In this article, I outline hermeneutic single-case efficacy design (HSCED), an interpretive approach to evaluating treatment causality in single therapy cases. This approach uses a mixture of quantitative and qualitative methods to create a network of evidence that first identifies direct demonstrations of causal links between therapy process and outcome and then evaluates plausible nontherapy explanations for apparent change in therapy. I illustrate the method with data from a depressed client who presented with unresolved loss and anger issues. 相似文献
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Hannon JP Nunn C Stolz B Bruns C Weckbecker G Lewis I Troxler T Hurth K Hoyer D 《Journal of molecular neuroscience : MN》2002,18(1-2):15-27
Somatostatin (SRIF, somatotropin release inhibiting factor), discovered for its inhibitory action on growth hormone (GH) secretion
from pituitary, is an abundant neuropeptide. Two forms, SRIF14 and SRIF28 exist. Recently, a second family of peptides with very similar sequences and features was described; the cortistatins (CST),
CST17 and CST29 which are brain selective. The five cloned SRIF receptors (sst1–5) belong to the G-protein coupled/heptathelical receptor family. Structural and operational features distinguish two classes
of receptors; SRIF1-sst2/sst3/sst5 (high affinity for octreotide or seglitide) and SRIF2=sst1/sst4 (very low affinity for the aforementioned ligands). The affinity of SRIF receptors for somatostatins and cortistatins is
equally high, and it is not clear whether selective receptors do exist for one or the other of the peptides. Several radiologlands
label all SRIF receptors, e.g., [125I]LTT-SRIF28, [125I]CGP23996, [125I]Tyr10cortistatin or [125I]Tyr11SRIF14. In contrast, [125I]Tyr3octreotide, [125I]BIM23027, [125I]MK678 or [125I]D-Trp8SRIF14 label predominantly SRIF1 sites, especially sst2 and possibly sst5 receptors. In brain, [125I]Tyr3octreotide binding equates with sst2 receptor mRNA distribution. Native SRIF2 receptors can be labeled with [125I]SRIF14 in the presence of high NaCl in brain (sst1) or lung (sst4) tissue. Short cyclic or linear peptide analogs show selectivity for sst2/sst5 (octreotide, lanreotide, BIM 23027), sst1 (CH-275), sst3 (sst3-ODN-8), or sst5 receptors (BIM 23268); although claims for selectivity have not always been confirmed. Beta peptides with affinity for SRIF
receptors are also reported. The general lack of SRIF receptor antagonists is unique for peptide receptors, although CYN 154806
is a selective and potent sst2 antagonist. Nonpeptide ligands are still rare, although a number of molecules have been reported with selectivity and potency
for sst1 (L 757,519), sst2 (L 779,976), sst3 (L 796,778), sst4 (NNC 26-9100, L 803,087) or sst1/sst5 receptors (L 817,018). Such molecules are essential to establish the role of SRIF receptors, e.g., sst1 in hypothalamic glutamate currents: sst2 in inhibiting release of GH, glucagon, TSH, gastric acid secretion, pain, seizures and tumor growth, and sst5 in vascular remodeling and inhibition of insulin and GH release. 相似文献
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