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Die statistische Auswertung von ordinalen Daten bei zwei Zeitpunkten und zwei Stichproben / The Statistical Analysis of Ordinal Data at two Timepoints and two GroupsSiemer, Alexander 03 April 2002 (has links)
No description available.
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Componentes de rendimento e características físico-químicas de fruto em genótipos de fisális submetidos a diferentes espaçamentos / Yield components and physicochemical characteristics of fruit in goldenberries genotypes under different spacingsColli, Mauro Porto 27 November 2015 (has links)
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Previous issue date: 2015-11-27 / FUMDES / Considering the potential of goldenberries culture in Santa Catarina incorporated into the cultivation of small fruits, the interest of consumers and producers and the need for further studies for the development of culture, this study aimed to characterize yield components and evaluate the characteristics Physical and chemical fruit of populations fisális submitted to different spacing between rows. They were evaluated six populations goldenberries under three spacing between rows in six periods of harvest. A block design at random in subdivided plots with three replications. The experimental setup consists factorial 3 x 6 x 6 for yield components and 3 x 6 for the physicochemical characteristics. To yield components were evaluated: total yield (t ha-1), income accumulated fruits (kg plant-1), backlog of fruits (no plant-1), fruit weight (g plant-1), diameter Polar (mm) and equatorial (mm), and cracked fruit percentage (%). For physical and chemical characteristics were evaluated: total soluble solids (° Brix), titratable acidity (% citric ac.), Maturation index, firmness (N) and fruit color index. Statistical analysis of data was performed by adjusting matrix of variance and covariance residual by-AIC Akaike information for the items of income and both studies were submitted to analysis of variance (Anova) for description of the results, and when significant, for qualitative variables we used the comparison test of Tukey (p=0.05), and the quantitative variables we used linear and nonlinear regression. The spacing influenced mass, total soluble solids, and the color index of the fruit evaluated goldenberries populations. Populations showed variability for equatorial diameter and titratable acidity, which are important characters for determining the shape and flavor of the fruit. Yield components showed the variation over periods of crops / Considerando o potencial da cultura do fisális em Santa Catarina incorporada ao cultivo das pequenas frutas, o interesse de consumidores e produtores e a necessidade de maiores estudos para o desenvolvimento da cultura, o presente trabalho teve por objetivo caracterizar os componentes de rendimento e avaliar as características físico-químicas de frutos de populações de fisális, submetidos a diferentes espaçamentos entre filas. Foram avaliadas seis populações de fisális, sob três espaçamentos entre filas em seis períodos de colheita. Foi utilizado um delineamento em blocos ao acaso em parcelas subdividas com três repetições. O arranjo experimental compõe esquema fatorial 3 x 6 x 6 para os componentes de rendimento e 3 x 6 para as características físico-químicas. Para os componentes de rendimento foram avaliados: rendimento total (t ha-1), rendimento de frutos acumulados (kg planta-1), número de frutos acumulados (nº planta-1), massa de fruto (g planta-1), diâmetro polar (mm) e equatorial (mm), e percentual de fruto rachados (%). Para as características físico-químicas foram avaliados: sólidos solúveis totais (º Brix), acidez total titulável (% ác. cítrico), índice de maturação, firmeza (N) e índice de cor dos frutos. A análise estatística dos dados foi realizada pelo ajuste de matrizes de variância e covariância residuais pelo critério de informação de Akaike-AIC para os componentes de rendimento e ambos os estudos foram submetidos à análise de variância univariada
(Anova) para descrição dos resultados, e quando significativos, para as variáveis qualitativas utilizou-se o teste de comparação de médias de Tukey (p=0,05), e para as variáveis quantitativas utilizou-se regressão linear e não linear. O espaçamento influenciou a massa, os sólidos solúveis totais e o índice de cor dos frutos das populações de fisális avaliadas. As populações apresentaram variabilidade para diâmetro equatorial e acidez titulável total, sendo estes importantes carácteres para determinação da forma e do sabor dos frutos. Os componentes de rendimento apresentaram variação ao longo dos períodos de colheitas
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Modelos não lineares mistos em estudos de degradabilidade ruminal in situ / Nonlinear mixed models in studies of in situ ruminal degradabilitySimone Daniela Sartorio 09 November 2012 (has links)
A principal fonte de proteína na nutrição dos ruminantes é a proteína de origem microbiana, sintetizada no processo fermentativo de degradação ruminal a partir de proteína dietética ou microbiana. Logo o conhecimento deste processo é de grande importância em estudos de avaliação de alimentos para estes animais. Modelos não lineares são amplamente utilizados nestes estudos, buscando estimar os parâmetros da cinética de degradação ruminal através de métodos clássicos de análise univariada. Como estes ensaios envolvem medidas repetidas, propõem-se o uso de modelos não lineares mistos que permitem que a função de regressão não linear dependa de efeitos fixos e aleatórios, o que pode resolver os problemas de correlação entre as medidas repetidas e heterogeneidade de variâncias das respostas. Neste trabalho foram utilizadas duas alternativas comuns de análise de dados de digestibilidade, e seus resultados foram comparados com os da abordagem que utiliza modelos não lineares mistos. Utilizou-se o modelo não linear de Orskov e McDonald (1979) para explicar a cinética de degradação ruminal da matéria seca (MS) e da fibra em detergente neutro (FDN) do feno de capim-Tifton 85, em novilhos alimentados com seis rações experimentais compostas por três diferentes combinações de volumoso(Vo):concentrado(Co) (70:30, 50:50 e 30:70%). Como volumoso foram utilizados fenos de capim-Tifton 85 de diferentes qualidades (4% e 10% de proteína bruta) e como concentrado, casca de soja, milho moído e farelo de girassol. A degradabilidade foi determinada pela técnica in situ e os dez tempos de incubação foram de: 3, 6, 12, 24, 48, 60, 72, 84, 96 e 120 horas. Originalmente o experimento foi delineado em quadrado latino (6×6) com seis novilhos mestiços fistulados (linhas), seis períodos (colunas) e seis tratamentos, em que nas parcelas tem-se uma estrutura de parcelas subdivididas, sendo as subparcelas, os tempos de incubação. O uso de modelos não lineares mistos na análise de dados de digestibilidade in situ é bastante atraente principalmente quando a pesquisa tem por objetivo entender o comportamento do processo de digestibilidade ao longo dos tempos de incubação. Além disso, quanto maior a variabilidade dos dados, a abordagem mista se torna mais indicada, reduzindo os erros padrão das estimativas dos parâmetros. Mesmo não incluindo a estrutura de delineamento experimental, os modelos não lineares mistos conseguem explicar bem a variabilidade extra, provocada pelos efeitos dos fatores associados ao delineamento, com a inclusão de efeitos aleatórios nos parâmetros do modelo de Orskov e McDonald (1979). O pacote estatístico nlme do R mostrou-se ágil e eficiente no ajuste dos modelos não lineares mistos e as suas ferramentas gráficas foram importantes na avaliação da qualidade dos ajustes e na escolha de modelos. / The main source of protein in ruminant nutrition is the protein of microbial origin, synthesized in the fermentation process of ruminal degradation starting from dietetics or microbial protein. Then, the knowledge of this process is of great importance in evaluation studies of food for these animals. Nonlinear models are widely used in these studies to estimate the parameters of ruminal degradation kinetics through the classical methods of univariate analysis. As these trials involve repeated measurements, we propose the use of nonlinear mixed models which allows that the nonlinear regression function depends on fixed and random effects, which can solve the problems of correlation between the repeated measurements and heterogeneity of variances of the responses. In this work, we used two common alternatives of digestibility data analysis, and their results were compared with the approach which uses nonlinear mixed model. We used the nonlinear model of Orskov and McDonald (1979) to explain the kinetics of ruminal degradation of dry matter (MS) and neutral detergent fiber (FDN) of the hay grass-Tifton 85, in steers fed experimental with six diets composed of three different combinations of forage(Vo):concentrate(Co) (70:30, 50:50 and 30:70%). As forage, we used hay grass-Tifton 85 of different qualities (4% and 10% crude protein) and as concentrate, soybean hulls, corn and sunflower meal. The degradability was determined by the in situ technique and the incubation times were 3, 6, 12, 24, 48, 60, 72, 84, 96 and 120 hours. Originally the experiment was designed as a Latin square (6 × 6) with six fistulated crossbred steers (lines), six periods (columns) and six treatments, in which the plots have a splitplot structure where the subplots were considered the times of incubation. The use of nonlinear mixed models in the analysis of the in situ digestibility data is quite attractive especially when the research aims to understand the process behavior digestibility over the incubation times. Moreover, the higher the variability of the data, the mixed approach becomes more suitable, reducing standard errors of the estimated parameters. Even excluding the structure of experimental design, the linear mixed models can explain well the extra variability caused by the effects of the factors associated with the design, with the inclusion of random effects in the model parameters of Orskov and McDonald (1979). The R statistical package nlme proved to be agile and efficient for the adjustment of nonlinear mixed models and its graphical tools were important in evaluating the quality of the adjustments and the choice of models.
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Análise de dados longitudinais em experimentos com cana-de-açúcar / Analysis of longitudinal data in experiments with sugar of caneEdjane Gonçalves de Freitas 25 February 2008 (has links)
Nesse trabalho foi abordada a situação em que observações de produtividade da cana-de-açúcar (TCH) foram tomadas na mesma unidade experimental em diferentes condições de avalições (anos). Foram avaliados os perfis médios de resposta de 48 genótipos de cana-de-açúcar em dois experimentos: Experimento 1 e Experimento 2, durante três e cinco anos respectivamente, ambos com o delineamento de blocos ao acaso. Esse tipo de planejamento produz uma forma de relação entre as observações tomadas na mesma unidade experimental, portanto requer outras suposições, além das usuais, para que análise seja correta e os testes produzam resultados válidos. Para que as inferências sobre as médias de produtividade sejam válidas e seguras é necessário que o modelo da matriz de covariância dos dados seja apropriado. Diante disso, foram avalidos três alterantivas de análise para dados longitudinais (medidas repetidas no tempo ), sendo utilizados portanto, o modelo univariado, conforme o planejamento do tipo \"split-plot on time\", que impõe forte restrição quanto a matriz de variâncias-covariâncias; o modelo multivariado, que utiliza uma matriz de variâncias-covariâncias não-estruturada e o modelo mistos, que possibilita a seleção de uma matriz que melhor representa os dados. Contudo, verificou-se que não houve diferença entre os resultados dos testes para as diferentes metodologias. Porém, é interessante a continuidade do estudo em relação ao modelo misto, pois devido a sua flexibilidade e precisão é possível obter estimativas mais seguras dos componentes de variância e predizer os valores genotípicos, que por fim poderá proporcionar a predição de produção de uma futura colheita para um determinado genótipo. / This work has been dealt with situation in which observations of productivity of sugar of cane (TCH) were taken in the same unit experimental in different condition of assessments (years). The response profiles average of 48 genotypes of sugar of cane were evaluated in two experiments: Experiment 1 and Experiment 2, for three and five years respectively, both with the randomized complete block design. This type of planning produces a form of relationship between the observations made in the same unit experimental therefore requires other assumptions, in addition to the usual, so that analysis is correct and the test results valid. To that inferences on the means of productivity are valid and safe it is necessary that the model of covariance matrix of the data is appropriate. Therefore, were evaluated three alternatives for analysis of longitudinal data (repeated measures over time), the univariate model as the planning of the split-plot on time which imposes strong restrictions on variances - covariances matrix, the multivariate model, which uses a non-structured variances - covariances matrix and mixed model, which they are enable the selection of a matrix that best represents the data. However, it was found that there was no difference between the results of tests for the different methodologies. But it is interesting the continuity of the study in relation to mixed model, because due to its flexibility and accuracy will be possible to obtain more reliable estimates of the variance components and predict the genotypic values, which ultimately could provide a prediction of production of a future harvest for a given genotype.
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Uma abordagem para análise de dados com medidas repetidas utilizando modelos lineares mistos / One approach to analyzing data with repeated measures using linear mixed modelsMichele Barbosa 11 September 2009 (has links)
No presente trabalho propôs-se uma abordagem simples visando à escolha de um modelo linear misto a ser ajustado a dados com medidas repetidas. A construção do modelo envolveu a escolha dos efeitos aleatórios, dos efeitos fixos e da estrutura de covariâncias utilizando técnicas gráficas e analíticas. O uso do Teste da Razão de Verossimilhança e dos Critérios de Informação de Akaike - AIC e de Schwarz - BIC pode levar a escolhas diferentes da estrutura de covariâncias, o que pode influenciar os resultados das inferências feitas sobre os parâmetros de efeitos fixos. A abordagem foi aplicada a conjuntos de dados resultantes de estudos agropecuários utilizando o software livre R. Foram feitas comparações dos resultados obtidos de modelos implementados com o proc mixed do SAS e com a função lme() do R, observando as vantagens e restrições destes dois softwares. / In this present work was proposed a simple approach to know how to choose a linear mixed model that can be adjustable to data with repeated measures. The construction of the model involved the choice of random effects, the fixed effects and covariance structure, using graphical and analytical techniques. The use of the Likelihood Ratio Test and the Akaike Information Criteria - AIC and Schwarz - BIC can lead to different choices of the structure of covariance, which may influence the results of inferences made about the parameters of fixed effects. The approach was applied to data sets that was resulted from farming studies using the software R. Comparisons of the results of models implemented were made with the proc mixed of SAS and with the function lme() of R, noting the advantages and limitations of these two softwares.
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The Feasibility of Assessing Infants’ Social Evaluations Using Within-Subject Repeated Measures in a Virtual FormatCrooks, Samantha 01 January 2021 (has links)
Foundational research on infant social evaluations (e.g., Hamlin et al., 2007; Hamlin et al., 2011; Hamlin & Wynn, 2011) has been cited over 2,500 times and infant researchers suggest these data show infants have an unlearned preference for prosocial others. However, several failed replications have been published, which might be attributable to the type of research methods used to investigate this question. A single measure of the dependent variable is ubiquitous among these studies; within-subject repeated measures are rarely used. In the current study, we adapted methods used by Hamlin and Wynn (2011) to a video-only format, due to COVID-19 restrictions; we extended their methods by including four puppet shows and four corresponding puppet choices to assess for choice stability within and across participants. Six infants were assessed; all but one infant failed to make all four choices and three sessions had to be terminated early due to fussiness. Among the four infants who made at least two choices, no infant showed a robust preference for the helper puppet, two infants chose a puppet on the same side at least three times, and one infant chose the hinderer on three of four opportunities. Our data suggest that a completely virtual method might not be feasible for assessing infants’ choices between two puppets presented on a screen. Suggestions for addressing the limitations of the current study and directions for future research are described.
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Confidence Intervals for a Ratio of Binomial Proportions Based on Paired DataBonett, Douglas, Price, Robert M. 15 September 2006 (has links)
Four interval estimation methods for the ratio of marginal binomial proportions are compared in terms of expected interval width and exact coverage probability. Two new methods are proposed that are based on combining two Wilson score intervals. The new methods are easy to compute and perform as well or better than the method recently proposed by Nam and Blackwelder. Two sample size formulas are proposed to approximate the sample size required to achieve an interval estimate with desired confidence level and width.
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The Use Of Post-Intervention Data From Waitlist Controls To Improve Estimation Of Treatment Effect In Longitudinal Randomized Controlled TrialsWalters, Kimberly Ann 11 September 2008 (has links)
No description available.
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What drives mandatory and voluntary risk reporting variations across Germany, UK and US?Elshandidy, Tamer, Fraser, I., Hussainey, K. 2014 June 1920 (has links)
No / This paper utilises computerised textual analysis to explore the extent to which both firm and country characteristics influence mandatory and voluntary risk reporting (MRR and VRR) variations both within and between non-financial firms across Germany, the UK and the US, over the period from 2005 to 2010. We find significant variations in MRR and VRR between firms across the three countries. Further, we find, on average, that German firms tend to disclose significantly higher (lower) levels of risk information mandatorily than UK (US) firms. German firms, on average, tend to reveal considerably higher (lower) levels of VRR than US (UK) firms. Our results document that MRR and VRR variations are significantly influenced by systematic risk, the legal system and cultural values. We also find that country and firm characteristics have higher explanatory power over the observed variations in MRR than over those in VRR.
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Exploring solution strategies that can enhance the achievement of low-performing grade 12 learners in some mathematical aspectsMachisi, Eric 06 1900 (has links)
The purpose of this study was to explore solution strategies that can enhance the achievement of low-performing Grade 12 learners in the following mathematical aspects: finding the general term of a quadratic sequence, factorising third degree polynomials, determining the centre and radius of a circle, and calculating the angle between two lines. A convenience sample of twenty-five low-performing Grade 12 learners from a secondary school in Capricorn District of Limpopo Province participated in the study which adopted a repeated-measures research design. Learners were exposed to multiple solution strategies and data were collected using achievement tests. Findings indicated significant differences in learners‟ average scores due to the solution strategies used. In determining the general term of a quadratic sequence, learners‟ scores were significantly higher when they used formula and the table method than with the method of residues and solving simultaneous equations. Synthetic division made learners to achieve better scores than long division and equating coefficients in factorising third degree polynomials. The use of formulae to find the centre and radius of a circle made learners to have better achievement scores than completing the square. In calculating the angle between two lines learners‟ scores were better using formula and the cosine rule than using theorems. It was concluded that exposing low-performing Grade 12 learners to multiple solution strategies would enhance their achievement in the mathematical aspects explored in the study. Some of the solution strategies that made learners to achieve better results were not in the prescribed mathematics textbooks. The study therefore recommends that mathematics teaching should not be textbook-driven and that low-performing Grade 12 learners should not be regarded as beyond redemption. / Mathematics Education / M.Sc. (Mathematics, Science and Technology Education)
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