976 resultados para variance ratio test


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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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The objective of this study was to characterize energetically beersmade withhoney. The tests of beer production weremade withninetreatments,threecombination of the originalextract concentrations (11, 13and 15 °Brix) and threepercentagesof honeyin the wort formulation(0, 20 and 40%).The experimentwas completely randomizedwith two replications, totaling eighteenplots.Themashingprocesswas performed byinfusion, with honey added in the boiling step. After clarified, the wort had its extract contents corrected with the addition of filtered water and was inoculated withlowfermentation yeast .The fermentation occurred at 10 ° C. The beer was manually bottled and stored in a freezer at 0 °C for 15 days, formaturation. The beers were chemically analyzed on proximate composition (moisture, protein, lipid, ash, and carbohydrate), alcohol content (% m / m) and then calculated the energy value. The results ofchemical analysis andenergetic valuesof the beerswere subjected to analysisof variance (F test) and the means werecompared byTukey testat 5% probability. The commonbeershad the lowestenergy value (31.05 to 31.95 kcal100g-1) in relation toextra(36.42 to 38.42 kcal100g-1) and strong(38.20 to 40.17 kcal100g-1) beers. Theincrease in the original extractin beerraises theircaloric values. The presenceof honeyin the formulationincreasedthe energetic valuesincommon andextrabeersand decreasedin strong.The levelsof alcohol andcarbohydratewere predominant in thebeer energetic values,beingpossible to observeadirect relation amongthese components ofbeer and theircaloric value.

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This study aimed to characterize the physical and chemical composition of ten items of arracacha grown in the municipality of São Manuel for the 2009 harvest. In the roots of the clones BGH (4560, 5741, 5744, 5746, 5747, 6414, 6513, 6525 and 7609) and the cultivar Amarela de Senador Amaral the characteristics evaluated were: color (L *, a * and b *) and moisture, ash, crude fiber, raw grease, protein, reducing sugars, total sugars and starch. After obtaining the data, an analysis was performed for the variance of test F and comparisons between the means made by the Tukey test at 5% probability. There was no significant difference to the results of luminosity (L *) while BGH 6414 and BGH 5744 showed the highest values for chroma and * BGH 5741, BGH 6414, BGH 7609, 'Amarela de Senador Amaral' BGH 5747 presented the highest chroma values for b *. Clones BGH 7609 and BGH 6414 showed significantly higher levels of dry matter and with the potential yield of agro-industrial processes it would be best suited in the form of frying. The materials that showed significantly larger amounts of ash were BGH 6525, BGH 5747, 'Amarela de Senador Amaral ", BGH 4560, BGH 5746, BGH 6513. Regarding the contents of fatty matter BGH 6525, BGH 5741 and BGH 5744 showed the highest levels. The results of BGH 7609 showed crude fiber significantly higher than the other materials tested, it can be used in diets composed of fibers. BGH 4560 and cultivar had the highest crude protein. BGH 5741 showed the lowest reducing sugar content among the clones, but not significantly different from results found for the cultivar. All clones showed total sugar levels were higher in the cultivar, which may have more flavor. BGH 5741, BGH 5746, BGH 6525 and BGH 6513 showed significantly higher starch content than the cultivar Amarela de Senador Amaral. From these results we conclude that the clones have similar color characteristics, and are potentially a nutritionally adequate substitute for the cultivar.

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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

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Evaluations of measurement invariance provide essential construct validity evidence. However, the quality of such evidence is partly dependent upon the validity of the resulting statistical conclusions. The presence of Type I or Type II errors can render measurement invariance conclusions meaningless. The purpose of this study was to determine the effects of categorization and censoring on the behavior of the chi-square/likelihood ratio test statistic and two alternative fit indices (CFI and RMSEA) under the context of evaluating measurement invariance. Monte Carlo simulation was used to examine Type I error and power rates for the (a) overall test statistic/fit indices, and (b) change in test statistic/fit indices. Data were generated according to a multiple-group single-factor CFA model across 40 conditions that varied by sample size, strength of item factor loadings, and categorization thresholds. Seven different combinations of model estimators (ML, Yuan-Bentler scaled ML, and WLSMV) and specified measurement scales (continuous, censored, and categorical) were used to analyze each of the simulation conditions. As hypothesized, non-normality increased Type I error rates for the continuous scale of measurement and did not affect error rates for the categorical scale of measurement. Maximum likelihood estimation combined with a categorical scale of measurement resulted in more correct statistical conclusions than the other analysis combinations. For the continuous and censored scales of measurement, the Yuan-Bentler scaled ML resulted in more correct conclusions than normal-theory ML. The censored measurement scale did not offer any advantages over the continuous measurement scale. Comparing across fit statistics and indices, the chi-square-based test statistics were preferred over the alternative fit indices, and ΔRMSEA was preferred over ΔCFI. Results from this study should be used to inform the modeling decisions of applied researchers. However, no single analysis combination can be recommended for all situations. Therefore, it is essential that researchers consider the context and purpose of their analyses.

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This paper examines the local power of the likelihood ratio, Wald, score and gradient tests under the presence of a scalar parameter, phi say, that is orthogonal to the remaining parameters. We show that some of the coefficients that define the local powers remain unchanged regardless of whether phi is known or needs to be estimated, where as the others can be written as the sum of two terms, the first of which being the corresponding term obtained as if phi were known, and the second, an additional term yielded by the fact that phi is unknown. The contribution of each set of parameters on the local powers of the tests can then be examined. Various implications of our main result are stated and discussed. Several examples are presented for illustrative purposes

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Twelve participants ran (9 km . h(-1)) to test two types of running shoes: replica and original shoes. Ground reaction force, plantar pressure and electromyographic activity were recorded. The shoes were tested randomly and on different days. Comparisons between the two experimental conditions were made by analysis of variance (ANOVA) test (P <= 0.05). The time to first peak, loading rate of the first peak and impulse of the first 75 ms of stance were significantly different between the shoes (P <= 0.05), revealing an increase of impact forces for the replica shoes. The peak plantar pressure values were significantly higher (P <= 0.05) when wearing replica shoes. During running, the contact area was significantly smaller (P <= 0.05) for the replica shoe. The electromyographic activity of the analysed muscles did not show changes between the two shoes in running. These findings suggest that the use of replica running shoes can increase the external load applied to the human body, but may not change the muscle activity pattern during locomotion. This new mechanical situation may increase the risk of injuries in these movements.

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In this paper we obtain asymptotic expansions, up to order n(-1/2) and under a sequence of Pitman alternatives, for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in the class of symmetric linear regression models. This is a wide class of models which encompasses the t model and several other symmetric distributions with longer-than normal tails. The asymptotic distributions of all four statistics are obtained for testing a subset of regression parameters. Furthermore, in order to compare the finite-sample performance of these tests in this class of models, Monte Carlo simulations are presented. An empirical application to a real data set is considered for illustrative purposes. (C) 2011 Elsevier B.V. All rights reserved.

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Ng and Kotz (1995) introduced a distribution that provides greater flexibility to extremes. We define and study a new class of distributions called the Kummer beta generalized family to extend the normal, Weibull, gamma and Gumbel distributions, among several other well-known distributions. Some special models are discussed. The ordinary moments of any distribution in the new family can be expressed as linear functions of probability weighted moments of the baseline distribution. We examine the asymptotic distributions of the extreme values. We derive the density function of the order statistics, mean absolute deviations and entropies. We use maximum likelihood estimation to fit the distributions in the new class and illustrate its potentiality with an application to a real data set.

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We derive asymptotic expansions for the nonnull distribution functions of the likelihood ratio, Wald, score and gradient test statistics in the class of dispersion models, under a sequence of Pitman alternatives. The asymptotic distributions of these statistics are obtained for testing a subset of regression parameters and for testing the precision parameter. Based on these nonnull asymptotic expansions, the power of all four tests, which are equivalent to first order, are compared. Furthermore, in order to compare the finite-sample performance of these tests in this class of models, Monte Carlo simulations are presented. An empirical application to a real data set is considered for illustrative purposes. (C) 2012 Elsevier B.V. All rights reserved.

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Kernkollaps-Supernovae werden von einem massiven Ausbruch niederenergetischer Neutrinos begleitet. Sie zählen zu den energiereichsten Erscheinungen im Universum und stellen die derzeit einzig bekannte Quelle extrasolarer Neutrinos dar.rnDie Detektion einer solchen Neutrinosignatur würde zu einem tieferen Verständnis des bislang unzureichend bekannten stellaren Explosionsmechanismus führen. rnDarüber hinaus würden neue Einblicke in den Bereich der Teilchenphysik und der Supernova-Modellierung ermöglicht. Das sich zur Zeit am geographischen Südpol im Aufbau befindliche Neutrinoteleskop IceCube wird 2011 fertig gestellt sein.rnIceCube besteht im endgültigen Ausbau aus 5160 Photovervielfachern, die sich in gitterförmiger Anordnung in Tiefen zwischen 1450m und 2450m unter der Eisoberfläche befinden. Durch den Nachweis von Tscherenkow-Photonenrnim antarktischen Gletscher ist es in der Lage, galaktische Supernovae über einen kollektiven Anstieg der Rauschraten in seinen Photonenvervielfachern nachzuweisen.rnIn dieser Arbeit werden verschiedene Studien zur Implementierung einer künstlichen Totzeit vorgestellt, welche korreliertes Rauschen unterdrücken und somit das Signal-Untergund-Verhältnis maximieren würden.rnEin weiterer Teil dieser Dissertation bestand in der Integration der Supernova-Datenakquise eine neue Experiment-Steuerungssoftware.rnFür den Analyseteil der Arbeit wurde ein Monte-Carlo für IceCube entwickelt und Neutinooszillations-Mechanismen und eine Reihe von Signalmodellen integriert. Ein Likelihoodhypothesen-Test wurde verwendet, um die Unterscheidbarkeit verschiedener Supernova- beziehungsweise Neutrinooszillations-Szenarien zu untersuchen. Desweiteren wurde analysiert inwieweit sich Schock-Anregungen und QCD-Phasenübergnag im Verlauf des Explosionsprozesses detektieren lassen.

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Estimation of the number of mixture components (k) is an unsolved problem. Available methods for estimation of k include bootstrapping the likelihood ratio test statistics and optimizing a variety of validity functionals such as AIC, BIC/MDL, and ICOMP. We investigate the minimization of distance between fitted mixture model and the true density as a method for estimating k. The distances considered are Kullback-Leibler (KL) and “L sub 2”. We estimate these distances using cross validation. A reliable estimate of k is obtained by voting of B estimates of k corresponding to B cross validation estimates of distance. This estimation methods with KL distance is very similar to Monte Carlo cross validated likelihood methods discussed by Smyth (2000). With focus on univariate normal mixtures, we present simulation studies that compare the cross validated distance method with AIC, BIC/MDL, and ICOMP. We also apply the cross validation estimate of distance approach along with AIC, BIC/MDL and ICOMP approach, to data from an osteoporosis drug trial in order to find groups that differentially respond to treatment.