Um estudo comparativo de L-estimadores de regressão

Orientador: Gabriela StangenhausDissertação (mestrado) - Universidade Estadual de Campinas , Instituto de Matematica, Estatistica e Ciencia da ComputaçãoResumo: Não informado.Abstract: Not informed.MestradoMestre em Estatístic

Heterogeneidade do desempenho de alunos da Unicamp, do ingresso à conclusão.

O objetivo deste trabalho é propor uma metodologia para avaliar o desempenho dos alunos da Universidade Estadual de Campinas, do ingresso à conclusão do curso. A amostra é composta por todos os ingressantes dessa universidade nos anos de 1997 a 2000, e a população que corresponde ao universo dos alunos ingressantes em todo o período de existência da universidade. O conjunto de dados disponível foi obtido a partir dos questionários socioculturais, aplicados pela Comissão Permanente de Vestibulares na inscrição do vestibular, e de informações acadêmicas fornecidas pela Diretoria Acadêmica da Universidade. É proposta uma metodologia com base na variável denominada "ganho relativo" sugerida por Dachs e Maia (2006). Essa nova metodologia fundamenta-se em medidas de diversidades propostas por Rao (1982) e na utilização de U-estatísticas. Propõem-se testes de homogeneidade para avaliar se existe diferença no desempenho entre alunos segundo alguns agrupamentos

Decomposability of high-dimensional diversity measures: Quasi-U-statistics, martingales and nonstandard asymptotics

In analyses of complex diversity, especially that arising in genetics, genomics, ecology and other high-dimensional (and sometimes low-sample-size) data models, typically subgroup decomposability (analogous to ANOVA decomposability) arises. For group divergence of diversity measures in a high-dimension low-sample-size scenario, it is shown that Hamming distance type statistics lead to a general class of quasi-U-statistics having, under the hypothesis of homogeneity, a martingale (array) property, providing a key to the study of general (nonstandard) asymptotics. Neither the stochastic independence nor homogeneity of the marginal probability laws plays a basic role. A genomic MANOVA model is presented as an illustration.Categorical Data Dependence DNA Genomics Hamming distance Orthogonal system Permutation measure Second-order asymptotics Second-order decomposability

Academic performance of students from entrance to graduation via quasi U-statistics: a study at a Brazilian research university

<div><p>We present novel methodology to assess undergraduate students' performance. Emphasis is given to potential dissimilar behaviors due to high school background and gender. The proposed method is based on measures of diversity and on the decomposability of quasi <i>U</i>-statistics to define average distances between and within groups. One advantage of the new method over the classical analysis of variance is its robustness to distributional deviation from the normality. Moreover, compared with other nonparametric methods, it also includes tests for interaction effects which are not rank transform procedures. The variance of the test statistic is estimated by jackknife and <i>p</i>-values are computed using its asymptotic distribution. A college education performance data is analyzed. The data set is formed by students who entered in the University of Campinas, Brazil, between 1997 and 2000. Their academic performance has been recorded until graduation or drop-out. The classical ANOVA points to significant effects of gender, type of high school and working status. However, the residual analysis indicates a highly significant deviation from normality. The quasi <i>U</i>-statistics nonparametric tests proposed here present significant effect of interaction between type of high school and gender but did not present a significant effect of working status. The proposed nonparametric method also results in smaller error variances, illustrating its robustness against model misspecification.</p></div

Heterogeneidade do desempenho de alunos da Unicamp, do ingresso à conclusão Heterogeneity in the performance of Unicamp students from admission to conclusion of undergraduated studies

O objetivo deste trabalho é propor uma metodologia para avaliar o desempenho dos alunos da Universidade Estadual de Campinas, do ingresso à conclusão do curso. A amostra é composta por todos os ingressantes dessa universidade nos anos de 1997 a 2000, e a população que corresponde ao universo dos alunos ingressantes em todo o período de existência da universidade. O conjunto de dados disponível foi obtido a partir dos questionários socioculturais, aplicados pela Comissão Permanente de Vestibulares na inscrição do vestibular, e de informações acadêmicas fornecidas pela Diretoria Acadêmica da Universidade. É proposta uma metodologia com base na variável denominada "ganho relativo" sugerida por Dachs e Maia (2006). Essa nova metodologia fundamenta-se em medidas de diversidades propostas por Rao (1982) e na utilização de U-estatísticas. Propõem-se testes de homogeneidade para avaliar se existe diferença no desempenho entre alunos segundo alguns agrupamentos.<br>The aim of this work is to propose a methodology to evaluate the performance of students at Unicamp [São Paulo State University at Campinas] from admission to graduation. The sample consists of all students enrolled in Unicamp from 1997 to 2000, and the population corresponds to the universe of students throughout the existence of the university. The available database was gathered from socio-cultural questionnaires applied by the University Commission on College Entrance Examination at the time of enrollment for the examination ("vestibular") and from academic information provided by the Unicamp Academic Studies Board. A methodology is proposed based on the "relative gain" variable suggested by Dachs and Maia (2006). This new methodology is based on the diversity measures proposed by Rao (1982) and on the use of U-statistics. Homogeneity tests have been proposed to assess whether there is a difference in performance among students from different groups

Influence of Leishmania (Viannia) braziliensis infection on the attractiveness of BALB/c mice to Nyssomyia neivai (Diptera: Psychodidae).

BACKGROUND:Phlebotomine sand flies are vectors for several pathogens, with Leishmania being the most important. In Brazil, the main aetiological agent of American cutaneous leishmaniasis (ACL) is Leishmania (Viannia) braziliensis, and Nyssomyia neivai is one of its main vectors in São Paulo state and other areas of South America. Similar to other haematophagous insects, sand flies use volatile compounds called kairomones to locate their hosts for blood meals. A possible increase in the attractiveness of hosts infected with Leishmania infantum to their vectors has been demonstrated. In the present study, we aimed to investigate whether L. braziliensis-infected hosts present higher attractiveness to Ny. neivai and to identify differences in the volatile compounds released by infected and uninfected mice. RESULTS:Behavioural experiments in which sand fly females directly fed on infected or uninfected mice showed no significant differences in the attractiveness of the mice or the blood volume ingested. Y-tube olfactometer bioassays also revealed no significant differences in the attractiveness of these hosts to Ny. neivai. No differences were observed in the profiles of the volatile compounds released by the two groups of mice. However, PCA and cluster analysis were able to classify the 31 identified compounds into three clusters according to their abundances. This classification showed a possible role for individual variation in the absence of differences in volatile profiles and attractiveness between infected and uninfected mice. CONCLUSION:In this first cross-sectional study with an aetiological agent of ACL, there were no statistically significant differences in the attractiveness of infected hosts to their vector