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The bootstrap method is a computer intensive statistical method that is widely used in performing nonparametric inference. Categorical data analysis, in particular the analysis of contingency tables, is commonly used in applied field. This work considers nonparametric bootstrap tests for the analysis of contingency tables. There are only a few research papers which exploit this field. The p-values of tests in contingency tables are discrete and should be uniformly distributed under the null hypothesis. The results of this article show that corresponding bootstrap versions work better than the standard tests. Properties of the proposed tests are illustrated and discussed using Monte Carlo simulations. This article concludes with an analytical example that examines the performance of the proposed tests and the confidence interval of the association coefficient. 相似文献
73.
Nonsmooth nonnegative matrix factorization (nsNMF) 总被引:3,自引:0,他引:3
Pascual-Montano A Carazo JM Kochi K Lehmann D Pascual-Marqui RD 《IEEE transactions on pattern analysis and machine intelligence》2006,28(3):403-415
We propose a novel nonnegative matrix factorization model that aims at finding localized, part-based, representations of nonnegative multivariate data items. Unlike the classical nonnegative matrix factorization (NMF) technique, this new model, denoted "nonsmooth nonnegative matrix factorization" (nsNMF), corresponds to the optimization of an unambiguous cost function designed to explicitly represent sparseness, in the form of nonsmoothness, which is controlled by a single parameter. In general, this method produces a set of basis and encoding vectors that are not only capable of representing the original data, but they also extract highly focalized patterns, which generally lend themselves to improved interpretability. The properties of this new method are illustrated with several data sets. Comparisons to previously published methods show that the new nsNMF method has some advantages in keeping faithfulness to the data in the achieving a high degree of sparseness for both the estimated basis and the encoding vectors and in better interpretability of the factors. 相似文献
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Macroscopic sliding between two solids is triggered by the propagation of a micro-slip front along the frictional interface. In certain conditions, sliding is preceded by the propagation of aborted fronts, spanning only part of the contact interface. The selection of the characteristic size spanned by those so-called precursors remains poorly understood. Here, we introduce a 1D toy model of precursors between a slider and a track in which the fronts are quasi-static self-healing slip pulses. When the slider’s thickness is large compared to the elastic correlation length and when the interfacial stiffness is small compared with the bulk stiffness, we provide an analytical solution for the length of the first precursor, \(\varLambda\) , and the shear stress field associated with it. These quantities are given as a function of the bulk material parameters, the frictional properties of the interface and the macroscopic loading conditions. Analytical results are in quantitative agreement with the numerical solution of the model. In contrast with previous models, our model predicts that \(\varLambda\) does not depend on the frictional breaking threshold of the interface. Our results should be relevant to the various systems in which self-healing slip pulses have been observed. 相似文献
77.
John F. Elliott David C. Lynch Tracy B. Braun 《Metallurgical and Materials Transactions B》1975,6(4):495-501
The analysis by Flood and Grjotheim1 of the equilibria between a metal and a fused slag utilizes the ionic behavior of the slag or salt, and it employs a reversible thermodynamic cycle. However, in the original analysis there appears to be an error in the use of free energy. A corrected treatment has been developed which involves a modest change and simplification in the original formulation. The revised analysis shows the importance of the thermodynamic behavior of ionic species in the slag, which may be nonideal. Data from the literature on slag-metal equilibria, for example: $$\left[ {Fe^{2 + } } \right] + \underline {Mn} = Fe\left( l \right) + \left[ {Mn^{2 + } } \right]$$ , are analyzed by the new formulation to obtain expressions for ratios of activity coefficients such as (γS2?/γO2?), (γMn2+/γFe2+) and [(γPO 4 3? )2/(γO2?)3] in terms of slag composition, the last two having been found to depend strongly on the oxygen-ion content of the slag. 相似文献
78.
Urinary amino acid excretion was determined in 31 leukemic patients and 29 normal individuals by rapid gas chromatographic analysis of 16 amino acids as their N-acetyl-n-propyl esters. The leukemic patients were concurrently undergoing, or had recently completed, chemotherapy. It was found that aspartic acid, threonine, and serine were of significance in distinguishing between patients "on" therapy and those "off" therapy. Patients with advanced disease have the greatest aminoaciduria, although both the normal and leukemic populations have wide individual ranges. Within both populations, men excrete a greater variety and quantity of amino acids than women. It is concluded that analysis of urinary amino acids represents a history of complex metabolic events, which is potentially useful for evaluating patient response to chemotherapy in leukemia. 相似文献
79.
The behavior of 24 children, aged 3-6 years, was recorded on video-tape. Simultaneously the ECG was recorded telemetrically. These observations were made during two pre-school educational programs lasting 90 minutes each: "Didactic games" and "Elementary music and movement program". For each child a scale was developed to show the correlation of mean heart-rate and well defined motor-activity. It was evident that the mean heart-rate was higher during the music program than during the didactic program, corresponding to the higher motor-activity. But it was found that in the didactic program the variation of the heart-rate within short intervals was higher due to the more frequent occurrence of respiratory arrhythmias. It was also seen that during the music program the children showed no signs of exertion as they did towards the end of the didactic program. Respiratory arrhythmias were not seen in children who according to the Schellong-test were classified as stable in their cardiovascular system. The arrhythmias occurred mainly when the children showed signs of fatigue. 相似文献
80.
Stochastic models are presented for the structure and conditioning of pads used in chemical-mechanical polishing of wafers. First the one-dimensional distribution function of surface depth in the case of a conditioned solid pad is described. Then, for characterizing the structure of a foamed pad, the theory of random closed sets is applied. An important distributional characteristic of a random closed set, the linear contact distribution function, yields the contribution to surface depth resulting from pores. As a special example the Boolean model is considered. This leads to a formula that describes the variability of the surface of a conditioned foamed pad after a certain time. Simulations and experimental data show a good agreement between theory and reality. 相似文献