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Pesquisas sob amostragem informativa utilizando o FBST; Surveys under informative sampling using the FBST

Azerêdo, Daniel Mendes
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 28/05/2013 Português
Relevância na Pesquisa
37.984365%
Pfeffermann, Krieger e Rinott (1998) apresentaram uma metodologia para modelar processos de amostragem que pode ser utilizada para avaliar se este processo de amostragem é informativo. Neste cenário, as probabilidades de seleção da amostra são aproximadas por uma função polinomial dependendo das variáveis resposta e concomitantes. Nesta abordagem, nossa principal proposta é investigar a aplicação do teste de significância FBST (Full Bayesian Significance Test), apresentado por Pereira e Stern (1999), como uma ferramenta para testar a ignorabilidade amostral, isto é, para avaliar uma relação de significância entre as probabilidades de seleção da amostra e a variável resposta. A performance desta modelagem estatística é testada com alguns experimentos computacionais.; Pfeffermann, Krieger and Rinott (1998) introduced a framework for modeling sampling processes that can be used to assess if a sampling process is informative. In this setting, sample selection probabilities are approximated by a polynomial function depending on outcome and auxiliary variables. Within this framework, our main purpose is to investigate the application of the Full Bayesian Significance Test (FBST), introduced by Pereira and Stern (1999)...

Metodologia para a prática projetual do design

Merino, Giselle Schmidt Alves Díaz
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Tese de Doutorado Formato: 1 v.| il., grafs.
Português
Relevância na Pesquisa
28.298447%
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Produção, 2014.; Tendo como ponto de partida a necessidade de pesquisas que contribuam para melhor compreender a prática projetual do Design, somada às limitadas aplicações práticas do Projeto Centrado no Usuário, o problema central desta pesquisa se configura a partir do seguinte questionamento: Como incorporar o Projeto Centrado no Usuário, com ênfase no Design Universal, na prática projetual do Design? Desta forma, o objetivo geral é desenvolver, aplicar e avaliar uma proposta de modelo para a prática projetual do Design, com base no projeto centrado no usuário e com ênfase no Design Universal. O desenvolvimento de projetos com ênfase no usuário é uma necessidade natural quando o foco está no ser humano. Neste sentido as formas de projetar devem considerar suas capacidades e limitações, sejam elas físicas e/ou cognitivas. A proposta metodológica da tese se divide em três Fases: Revisão da Literatura (Fase 1); Desenvolvimento do Modelo (Fase 2) e Aplicação e Avaliação do Modelo (Fase 3). Os resultados alcançados permitem inferir que o Modelo Proposto (Guia de Orientação para o Desenvolvimento de Projetos - GODP) se apresenta como uma ferramenta adequada à prática projetual...

Web Survey Design and Administration

COUPER, MICK P.; TRAUGOTT, MICHAEL W.; LAMIAS, MARK J.
Fonte: Oxford University Press Publicador: Oxford University Press
Tipo: Artigo de Revista Científica Formato: text/html
Português
Relevância na Pesquisa
38.651934%
Many claims are being made about the advantages of conducting surveys on the Web. However, there has been little research on the effects of format or design on the levels of unit and item response or on data quality. In a study conducted at the University of Michigan, a number of experiments were added to a survey of the student population to assess the impact of design features on resulting data quality. A sample of 1,602 students was sent an e-mail invitation to participate in a Web survey on attitudes toward affirmative action. Three experiments on design approaches were added to the survey application. One experiment varied whether respondents were reminded of their progress through the instrument. In a second experiment, one version presented several related items on one screen, while the other version presented one question per screen. In a third experiment, for one series of questions a random half of the sample clicked radio buttons to indicate their answers, while the other half entered a numeric response in a box. This article discusses the overall implementation and outcome of the survey, and it describes the results of the imbedded design experiments.

Estrat?gia de utiliza??o de topsoil na restaura??o ambiental

Amaral, Luise Andrade
Fonte: UFVJM Publicador: UFVJM
Tipo: Dissertação de Mestrado
Português
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27.952056%
ABSTRACT The aim of this study was to evaluate two types of topsoil, as well as ways to use them as a source of propagules, nutrients, microorganisms, organic matter etc., The recovery of degraded areas different. The experiments were conducted in areas belonging to the mining company Anglo American iron headquartered in the municipality of Concei??o do Mato Dentro, Minas Gerais, however, as the company is still in the installation phase, the assigned areas are not degraded by the process of extraction of ore, one in waste dump and the other in degraded pasture. The work was organized in chapters where the first presents a literature review on all subjects involved in the study. The second chapter presents the evaluation of natural regeneration and soil cover of a waste dump in the dry and wet deposition from the haul topsoil from ferruginous rocky fields in the municipality of Concei??o do Mato Dentro, Minas Gerais. The third chapter presents approaches to the use of topsoil in the recovery of a degraded pasture. In the area of Chapter 2 were systematically installed 26 plots and a control plot 1 square meter, we characterized the physical and chemical properties of the substrates with and without topsoil. For floristic identification were two surveys one in July 2012 (early dry season) and the other in November 2012 (rainy season). The ground cover was visually estimated by the percentage of live coverage...

How Do Ex Ante Simulations Compare with Ex Post Evaluations? Evidence from the Impact of Conditional Cash Transfer Programs

Leite, Phillippe; Narayan, Ambar; Skoufias, Emmanuel
Fonte: Banco Mundial Publicador: Banco Mundial
Português
Relevância na Pesquisa
37.985095%
This paper compares the ex ante simulation of the impacts of conditional cash transfer programs against the ex post estimates of impacts obtained from experimental evaluations. Using data on program-eligible households in treatment areas from the same baseline surveys that are used for experimental evaluations of conditional cash transfer programs in Mexico and Ecuador, the authors use a micro-simulation model to derive ex ante estimates of the impact of the programs on enrollment rates and poverty. The estimates reveal that ex ante predictions of certain impacts of conditional cash transfer programs match up well against the benchmark estimates of ex post experimental studies. The findings seem to support the use of this model to assess the potential impact and cost efficiency of a conditional cash transfer program ex ante, in order to inform decisions about how the program would be designed.

Evaluating the Impact of Development Projects on Poverty : A Handbook for Practitioners

Baker, Judy L.
Fonte: Washington, DC: World Bank Publicador: Washington, DC: World Bank
Português
Relevância na Pesquisa
58.92241%
Very little is known about the actual impact of projects on the poor. Many are reluctant to carry out impact evaluations because they are deemed expensive, time consuming, and technically complex, and because the findings can be politically sensitive. Yet a rigorous evaluation can be powerful in assessing the appropriateness and effectiveness of programs. Evaluating impact is particularly critical in developing where resources are scarce and every dollar spent should aim to maximize its impact on poverty reduction. This handbook seeks to provide project managers and policy analysts with the tools needed for evaluating project impact. It is aimed at readers with a general knowledge of statistics. Chapter 1 presents an overview of concepts and methods, Chapter 2 discusses key steps and related issues to consider in implementation, Chapter 3 illustrates various analytical techniques through a case study, and Chapter 4 includes a discussion of lessons that have been reviewed for this handbook. The case studies, included in Annex I...

Evaluating the Impact of Conditional Cash Transfer Programs : Lessons from Latin America

Rawlings, Laura B.; Rubio, Gloria M.
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
Relevância na Pesquisa
58.031562%
Unlike most development initiatives, conditional cash transfer programs recently introduced in the Latin America and the Caribbean region have been subject to rigorous evaluations of their effectiveness. These programs provide money to poor families, conditional on certain behavior, usually investments in human capital-such as sending children to school or bringing them to health centers on a regular basis. Rawlings and Rubio review the experience in evaluating the impact of these programs, exploring the application of experimental and quasi-experimental evaluation methods and summarizing results from programs launched in Brazil, Honduras, Jamaica, Mexico, and Nicaragua. Evaluation results from the first generation of programs in Brazil, Mexico, and Nicaragua show that conditional cash transfer programs are effective in promoting human capital accumulation among poor households. There is clear evidence of success in increasing enrollment rates, improving preventive health care, and raising household consumption. Despite this promising evidence...

Micro-Level Estimation of Welfare

Elbers, Chris; Lanjouw, Jean O.; Lanjouw, Peter
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Português
Relevância na Pesquisa
48.21613%
The authors construct and derive the properties of estimators of welfare that take advantage of the detailed information about living standards available in small household surveys and the comprehensive coverage of a census or large sample. By combining the strengths of each, the estimators can be used at a remarkably disaggregated level. They have a clear interpretation, are mutually comparable, and can be assessed for reliability using standard statistical theory. Using data from Ecuador, the authors obtain estimates of welfare measures, some of which are quite reliable for populations as small as 15,000 households--a "town." They provide simple illustrations of their use. Such estimates open up the possibility of testing, at a more convincing intra-country level, the many recent models relating welfare distributions to growth and a variety of socioeconomic and political outcomes.

Integrating Qualitative Methods into Investment Climate Impact Evaluations

Mendoza Alcantara, Alejandra; Woolcock, Michael
Fonte: World Bank Group, Washington, DC Publicador: World Bank Group, Washington, DC
Português
Relevância na Pesquisa
28.212102%
Incorporating qualitative methods into the evaluation of development programs has become increasingly popular in recent years, both for the distinctive insights such approaches can bring in their own right and because of their capacity to complement the strengths -- and where necessary correct some of the weaknesses -- of quantitative approaches. Some initial work deploying mixed methods has been undertaken in the assessment of investment climate reforms, but considerable room for expansion exists. This paper summarizes some of the key principles and practices underpinning mixed methods evaluations in development, highlight some notable examples of how such work has been conducted (and the particular contributions it has made), and offers some guidelines for those seeking to increase the sophistication and utility of qualitative methods in the evaluation of investment climate reforms.

Mangiferin as a Biomarker for Mango Anthracnose Resistance

Pierre, Herma
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
87.7062%
Mangos (Mangifera indica L.) are tropical/subtropical fruits belonging to the plant family Anacardiaceae. Anthracnose is the most deleterious disease of mango both in the field and during postharvest handling. It is most commonly caused by the Colletotrichum gloeosporioides complex. Mangiferin, a xanthanoid compound found in at least twelve plant families worldwide (Luo et al., 2012), is present in large amounts of the leaves and edible mangos. Even though this compound plays a pivotal role in the plant’s defense against biotic and abiotic stressors, no correlations been made between the compound and mango anthracnose resistance. Mangos were collected, grouped according to their countries of origin, and evaluated for their mangiferin concentrations at four different stages of development. Extracts of interest were then tested against different strains of C. gloeosporioides. The results demonstrated that mangiferin concentrations are significantly different at different stages in fruit development. The antifungal assays were inconclusive.

The Effects of the Use of Technology In Mathematics Instruction on Student Acheivement

Myers, Ron Y
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
87.72987%
The purpose of this study was to examine the effects of the use of technology on students’ mathematics achievement, particularly the Florida Comprehensive Assessment Test (FCAT) mathematics results. Eleven schools within the Miami-Dade County Public School System participated in a pilot program on the use of Geometers Sketchpad (GSP). Three of these schools were randomly selected for this study. Each school sent a teacher to a summer in-service training program on how to use GSP to teach geometry. In each school, the GSP class and a traditional geometry class taught by the same teacher were the study participants. Students’ mathematics FCAT results were examined to determine if the GSP produced any effects. Students’ scores were compared based on assignment to the control or experimental group as well as gender and SES. SES measurements were based on whether students qualified for free lunch. The findings of the study revealed a significant difference in the FCAT mathematics scores of students who were taught geometry using GSP compared to those who used the traditional method. No significant differences existed between the FCAT mathematics scores of the students based on SES. Similarly, no significant differences existed between the FCAT scores based on gender. In conclusion...

Measuring Hotel Service Quality: Tools for Gaining the Competitive Edge

Ford, Robert C.; Bach, Susan A.
Fonte: FIU Digital Commons Publicador: FIU Digital Commons
Tipo: Artigo de Revista Científica Formato: application/pdf
Português
Relevância na Pesquisa
77.994175%
As the hotel industry grows more competitive, quality guest service becomes an increasingly important part of managers' responsibility measuring the quality of service delivery is facilitated when managers know what types of assessment methods are available to them. The authors present and discuss the following available measurement techniques and describe the situations where they best meet the needs of hotel managers: management observation, employee feedback programs, comment cards, mailed surveys, personal and telephone interviews, focus groups, and mystery shopping.

Missing(ness) in Action : Selectivity Bias in GPS-Based Land Area Measurements

Kilic, Talip; Zezza, Alberto; Carletto, Calogero; Savastano, Sara
Fonte: World Bank, Washington, DC Publicador: World Bank, Washington, DC
Tipo: Publications & Research :: Policy Research Working Paper; Publications & Research
Português
Relevância na Pesquisa
48.3355%
Land area is a fundamental component of agricultural statistics, and of analyses undertaken by agricultural economists. While household surveys in developing countries have traditionally relied on farmers' own, potentially error-prone, land area assessments, the availability of affordable and reliable Global Positioning System (GPS) units has made GPS-based area measurement a practical alternative. Nonetheless, in an attempt to reduce costs, keep interview durations within reasonable limits, and avoid the difficulty of asking respondents to accompany interviewers to distant plots, survey implementing agencies typically require interviewers to record GPS-based area measurements only for plots within a given radius of dwelling locations. It is, therefore, common for as much as a third of the sample plots not to be measured, and research has not shed light on the possible selection bias in analyses relying on partial data due to gaps in GPS-based area measures. This paper explores the patterns of missingness in GPS-based plot areas...

When Does Rigorous Impact Evaluation Make a Difference? The Case of the Millennium Villages

Clemens, Michael A.; Demombynes, Gabriel
Fonte: Banco Mundial Publicador: Banco Mundial
Tipo: Publications & Research :: Policy Research Working Paper
Português
Relevância na Pesquisa
48.619883%
When is the rigorous impact evaluation of development projects a luxury, and when a necessity? This Paper studies one high-profile case: the Millennium Villages Project (MVP), an experimental and intensive package intervention to spark sustained local economic development in rural Africa. it illustrates the benefits of rigorous impact evaluation in this setting by showing that estimates of the project's effects depend heavily on the evaluation method. Comparing trends at the MVP intervention sites in Kenya, Ghana, and Nigeria to trends in the surrounding areas yields much more modest estimates of the project's effects than the before-versus-after comparisons published thus far by the MVP. Neither approach constitutes a rigorous impact evaluation of the MVP, which is impossible to perform due to weaknesses in the evaluation design of the project's initial phase. These weaknesses include the subjective choice of intervention sites, the subjective choice of comparison sites, the lack of baseline data on comparison sites...

Endogenous post-stratification in surveys: classifying with a sample-fitted model

Breidt, F. Jay; Opsomer, Jean D.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 14/03/2008 Português
Relevância na Pesquisa
28.45466%
Post-stratification is frequently used to improve the precision of survey estimators when categorical auxiliary information is available from sources outside the survey. In natural resource surveys, such information is often obtained from remote sensing data, classified into categories and displayed as pixel-based maps. These maps may be constructed based on classification models fitted to the sample data. Post-stratification of the sample data based on categories derived from the sample data (``endogenous post-stratification'') violates the standard post-stratification assumptions that observations are classified without error into post-strata, and post-stratum population counts are known. Properties of the endogenous post-stratification estimator are derived for the case of a sample-fitted generalized linear model, from which the post-strata are constructed by dividing the range of the model predictions into predetermined intervals. Design consistency of the endogenous post-stratification estimator is established under mild conditions. Under a superpopulation model, consistency and asymptotic normality of the endogenous post-stratification estimator are established, showing that it has the same asymptotic variance as the traditional post-stratified estimator with fixed strata. Simulation experiments demonstrate that the practical effect of first fitting a model to the survey data before post-stratifying is small...

Scaling-up in estuaries: The Feasibility of using small scale results to draw large scale conclusions

Scheiner, Christopher
Fonte: Rochester Instituto de Tecnologia Publicador: Rochester Instituto de Tecnologia
Tipo: Tese de Doutorado
Português
Relevância na Pesquisa
38.218018%
Estuarine ecosystems are dynamic, heterogeneous ecosystems that are increasingly impacted by human activities, particularly excess nutrient loading and the resulting eutrophication. Much of the descriptive research investigating large-scale eutrophication is performed using field surveys and small-scale, manipulative microcosm experiments. To investigate confounding effects of scale and heterogeneity, we conducted a large-scale field survey of benthic conditions in West Falmouth Harbor (WFH), Cape Cod, Massachusetts, and compared our results to those observed in microcosm studies that utilized sediments and macrofauna from WFH. We used geographic information systems to estimate field condition heterogeneity and design an appropriate sampling strategy, and geostatistical interpolation methods to construct a dataset for the whole estuary based on our disparate sampling stations. Macroinvertebrate distribution was patchy, with somewhat lower densities than were used in experiments. The range of oxygen consumption rates (field 1.1-5.4; microcosm 1.0-9.3 mmol m-2 h-1) and benthic chlorophyll a (field 16-218; microcosm 30-263 mg m-2) were loosely comparable between field and microcosms. Porewater ammonium was higher in the microcosms (field 0-84; microcosm 28-1690 μM)...

Sample sizes for estimating key ecosystem characteristics in a tropical terra firme rainforest

Metcalfe, Daniel; Meir, Patrick; Aragão, Luiz Eduardo O C; da Costa, Antonio Carlos Lola; Almeida, Samuel; Braga, Alan; Goncalves, Paulo; Athaydes, Joao; Malhi, Yadvinder; Williams, Mathew
Fonte: Elsevier Publicador: Elsevier
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
48.102974%
This study evaluated the sample sizes necessary to estimate several soil and vegetation characteristics within 10% confidence intervals with 95% probability in three terra firme tropical rainforest sites. Across all three plots, the most spatially heterogeneous variables were measurements of total standing crop root mass, ground surface litter mass, litter fall, root growth and soil respiration which required, on average, 152, 105, 52, 45 and 28 samples, respectively to estimate mean values within 10% confidence intervals with 95% probability. Leaf area index measurements integrated canopy characteristics over a relatively large spatial area and therefore only required five samples, on average, to achieve the same degree of precision. Measurements of soil temperature, moisture, carbon and nitrogen content in the surface 30 cm soil layer displayed the lowest degree of spatial variation: requiring a maximum of seven samples to estimate mean values within 10% confidence intervals with 95% probability. This study, together with a review of data from similar ecosystems, suggests that standing crop root mass, root growth, litter fall and ground surface litter mass are usually acutely under-sampled, which could impede detection and interpretation of patterns and processes in these potentially important ecosystem characteristics. This information may assist researchers to design effective sampling strategies for field experiments...