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abstract: Mediation analysis is a statistical approach that examines the effect of a treatment (e.g., prevention program) on an outcome (e.g., substance use) achieved by targeting and changing one or more intervening variables (e.g., peer drug use norms). The increased use of prevention intervention programs with outcomes measured at multiple time points following the intervention requires multilevel modeling techniques to account for clustering in the data. Estimating multilevel mediation models, in which all the variables are measured at individual level (Level 1), poses several challenges to researchers. The first challenge is to conceptualize a multilevel mediation model by clarifying the underlying statistical assumptions and implications of those assumptions on cluster-level (Level-2) covariance structure. A second challenge is that variables measured at Level 1 potentially contain both between- and within-cluster variation making interpretation of multilevel analysis difficult. As a result, multilevel mediation analyses may yield coefficient estimates that are composites of coefficient estimates at different levels if proper centering is not used. This dissertation addresses these two challenges. Study 1 discusses the concept of a correctly specified multilevel mediation model by examining the underlying statistical assumptions and implication of those assumptions on Level-2 covariance structure. Further, Study 1 presents analytical results showing algebraic relationships between the population parameters in a correctly specified multilevel mediation model. Study 2 extends previous work on centering in multilevel mediation analysis. First, different centering methods in multilevel analysis including centering within cluster with the cluster mean as a Level-2 predictor of intercept (CWC2) are discussed. Next, application of the CWC2 strategy to accommodate multilevel mediation models is explained. It is shown that the CWC2 centering strategy separates the between- and within-cluster mediated effects. Next, Study 2 discusses assumptions underlying a correctly specified CWC2 multilevel mediation model and defines between- and within-cluster mediated effects. In addition, analytical results for the algebraic relationships between the population parameters in a CWC2 multilevel mediation model are presented. Finally, Study 2 shows results of a simulation study conducted to verify derived algebraic relationships empirically. / Dissertation/Thesis / Ph.D. Psychology 2010

Este trabalho visa propor uma metodologia de análise da variabilidade do tempo de atraso de propagação no FPGA. Para alcançar esse objetivo são utilizados três circuitos diferentes: o circuito 1 mede a diferença de atrasos de dois circuitos, o circuito 2 identifica o atraso menor de dois circuitos e, por fim, o terceiro circuito que consiste do oscilador em anel. Cada circuito foi avaliado individualmente numa estrutura BIST, implementada nos FPGA XC3S200-FT256 e EP2C35F672C6. Os métodos utilizados para análise dos dados foram a média móvel, o plano de mínimos quadrados e o teste t-student. A metodologia permitiu mostrar a variabilidade within-die e suas componentes sistêmica e randômica. / This work aims to propose a methodology of analysis of variability of propagation-delay time in FPGA. To achieve this goal three different circuits are implemented: the circuit 1 measures the delay difference of two logic paths, the circuit 2 identifies smallest delay of two logic paths, and finally the third circuit consists of a ring oscillator. Each circuit has been assessed individually in a BIST structure, implemented in FPGAs XC3S200-FT256 and EP2C35F672C6. The methods used for data analysis were the moving average, least-squares plane and the t-student test. The methodology has allowed to evaluate the within-die variability and its systemic and random components.

Explaining a phenomenon often requires identification of an underlying relationship between two variables. However, it is common practice in psychological research to sample only a few values of an independent variable. Young, Cole, and Sutherland (2012) showed that this practice can impair model selection in between-subject designs. The current study expands that line of research to within-subjects designs. In two Monte Carlo simulations, model discrimination under systematic sampling of 2, 3, or 4 levels of the IV was compared with that under random uniform sampling and sampling from a Halton sequence. The number of subjects, number of observations per subject, effect size, and between-subject parameter variance in the simulated experiments were also manipulated. Random sampling out-performed the other methods in model discrimination with only small, function-specific costs to parameter estimation. Halton sampling also produced good results but was less consistent. The systematic sampling methods were generally rank-ordered by the number of levels they sampled.

CARNEIRO, Waltersar José de Mesquita. O encadeamento argumentativo na teoria da argumentação na língua. 2006. 96f. – Dissertação (Mestrado) – Universidade Federal do Ceará, Departamento de Letras Vernáculas, Programa de Pós-graduação em Linguística, Fortaleza (CE), 2006. / Submitted by Márcia Araújo (marcia_m_bezerra@yahoo.com.br) on 2014-08-19T14:34:42Z No. of bitstreams: 1 2006_dis_wjmcarneiro.pdf: 5814790 bytes, checksum: bb8edfbf825c3989550872826cfe1b0c (MD5) / Approved for entry into archive by Márcia Araújo(marcia_m_bezerra@yahoo.com.br) on 2014-08-19T16:39:37Z (GMT) No. of bitstreams: 1 2006_dis_wjmcarneiro.pdf: 5814790 bytes, checksum: bb8edfbf825c3989550872826cfe1b0c (MD5) / Made available in DSpace on 2014-08-19T16:39:37Z (GMT). No. of bitstreams: 1 2006_dis_wjmcarneiro.pdf: 5814790 bytes, checksum: bb8edfbf825c3989550872826cfe1b0c (MD5) Previous issue date: 2006 / This paper presents a theoretical discussion on the Theory of Argumentation within Language – TAL, such as proposed by Oswald Ducrot and his collaborators. Our main objective is to investigate how the fundamental principles of TAL have been used by authors who deal with the notion of argumentative chaining. Since the publication of "The Argumentation within Language", in 1983, by Anscombre and Ducrot, some TAL basic principles have been modified, with direct consequences to the notion of argumentative chaining. Thus, this paper aims at checking if the authors who have been using TAL principles have followed the relevant modifications to the basic theory. In order to limit the scope of our work to the argumentation field, we have looked at the historical background of the discussions on the topic, from the first uses of the term in the Classic Antiquity ‘myths’ to the postulation of the Theory of Argumentation within Language. On each historical moment of the reflection on argumentation, we checked which principles have influenced Ducrot’s theory. As a corpus for this study, we selected some theoretical books in the areas of Textual Linguistics and Discourse Analysis. Those texts contain references to concepts derived from Ducrot’s theory, which allowed us to observe how concepts such as “argumentative operator” and “polyphony” have been used in these books, and above all to check if such concepts have followed, in these texts, all the theoretical reformulations that mark TAL theory. / A presente dissertação apresenta uma discussão teórica sobre a Teoria da Argumentação na Língua – TAL, teoria apresentada por Oswald Ducrot e colaboradores. O objetivo principal deste trabalho é verificar como os pressupostos da TAL têm sido utilizados por autores que tratam da noção de encadeamento argumentativo. Como a Tal passou, desde a publicação de “A argumentação na língua”, em 1983 por Anscombre e Ducrot, por modificações em alguns de seus pressupostos, que interferiram diretamente na noção de encadeamento argumentativo, buscamos verificar se os autores que utilizaram os pressupostos da TAL acompanharam as respectivas alterações da teoria. Com o propósito de delimitar a área de abrangência de nosso trabalho dentro do campo da argumentação, fizemos um percurso histórico sobre o tema, partindo dos primeiros usos do termo, através dos ‘mitos’ da Antiguidade Clássica até a postulação da Teoria da Argumentação na Língua. A cada momento histórico do tratamento da argumentação, verificamos quais postulados influenciaram a teoria ducrotiana. Selecionamos como objeto de verificação algumas obras teóricas da área da Lingüística Textual e da área da Análise do Discurso, que nos permitiram, pelo fato de conterem referências a conceitos advindos da teoria ducrotiana, verificar de que forma conceitos como ‘operador argumentativo’ e ‘polifonia’ foram utilizados nessas obras, observando principalmente se elas acompanharam todas as reformulações teóricas que caracterizam a própria TAL.