• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 119
  • 51
  • 9
  • 8
  • 7
  • 6
  • 4
  • 4
  • 3
  • 3
  • 2
  • 2
  • 2
  • 1
  • 1
  • Tagged with
  • 250
  • 250
  • 160
  • 32
  • 32
  • 31
  • 28
  • 28
  • 26
  • 23
  • 21
  • 19
  • 18
  • 17
  • 16
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
11

Emigração no Paraguai: efeitos das remessas / Emigration in Paraguay: effects of remittances

Blanca Nidia Aquino Sanchez 02 March 2011 (has links)
Neste trabalho analisou-se o impacto das remessas financeiras sobre os patrimônios dos ativos nos domicílios, no país de origem. Utilizamos dados da Encuesta Permanente de Hogares de 2008, os quais foram fornecidos pelo órgão Dirección General de Estadística, Encuestas y Censos do Paraguai. Com estes dados realizamos uma comparação entre os domicílios com e sem remessas, independente de terem ou não emigrantes. A metodologia utilizada para realizar a comparação foi o Propensity Score Matching (PSM) com dois algoritmos, Vizinhos Próximos e Kernel. Os patrimônios dos ativos são carros, aluguéis e combinados. Os resultados em todos os casos foram estatisticamente significativos, porém, negativos. Com amesma metodologia e os mesmos dados, comparamos apenas os domicílios com emigrantes, e os resultados continuaram negativos, porém, com nível de significância menor. / In this study we analyzed the impact of remittances on financial assets in the wealth of households in the country of origin. We use data from the Encuesta Permanente Hogares 2008, which were provided by the agency Dirección General de Estadística, Encuestas y Censos of Paraguay. With these data we performed a comparison between households with and without remittances, regardless of whether or not immigrants. The methodology for conducting the comparison was the Propensity Score Matching (PSM) with two algorithms, Kernel and Nearest Neighbors. The stockholders\' assets are cars, rentals and combined. The results in all cases were statistically significant, but negative. With the same methodology and same data, comparing only households with migrants, the results remained negative, but with lower significance level.
12

Impactos da atividade inovativa: um estudo para a indústria paulista / Impacts of innovation activity: a study for the paulista industry

Gustavo Assunção Faria 28 February 2008 (has links)
A presente dissertação visa avaliar, a partir do uso dos dados da Pesquisa de Atividade Econômica Paulista - PAEP - do ano de 1996, da RAIS - Relação Anual de Informações Sociais de 1992, 1993, 1997 e 1998 e da SECEX - Secretaria do Comércio Exterior - dos anos de 1992 e 1993, a relação entre a atividade de inovação tecnológica e os potenciais impactos produzidos sobre o nível de emprego e sobre o nível de renda na indústria paulista entre os anos de 1997 e 1998. Como a inovação não é um evento aleatório, há o viés de seleção da amostra, de tal sorte que uma comparação direta entre os efeitos da inovação sobre certas variáveis daquelas firmas que inovaram com aquelas que não inovaram, na situação de ter havido inovação, produziria vieses. Tal problema é resolvido neste trabalho por meio do Propensity Score Matching, que visa o pareamento de unidades tratamento - controle para a obtenção dos resultados intentados, a saber, a variação na renda e no nível de emprego. Ademais, de modo a inibir a presença de efeitos não observáveis, recorre-se ao método de Diferenças em Diferenças (DID). Os resultados obtidos atestam para um aumento, na média, do nível de emprego para quase todos os tipos de atividade inovativa empreendidas. Em contrapartida, os achados se revelaram estatisticamente insignificantes para a variação de renda, também em quase todos os tipos de inovação. / This work intends to analyze, by the usage of three different data sources, PAEP (1996), RAIS - Relação Anual de Informações Sociais (1992, 1993, 1997, and 1998) and SECEX - Secretaria do Comércio Exterior (from 1992, and 1993) the relationship, if that exists, between innovation and its potential impacts over employment level as well as salaries during the 1997 - 1998 period. Once innovation activity cannot be considered as a random event, we incur in the well known selection bias problem. Consequently, a direct comparison of the innovation impacts between those firms which effectively innovated with those which did not innovate would be misleading. Such a problem may be corrected with the Propensity Score Matching, which consists in the establishment of treatment - control pairs in order to obtain the results previously searched. Moreover, in an attempt to control for the unobserved effects, it is applied the Differences in Differences Methodology (DID). Results obtained show that, on the one hand, for almost all the innovation activities considered, there was an increment in the level of employment. On the other hand, for most of the cases, there were not statistically significant results for an impact of innovation activities on the level of salaries.
13

Efeito da desigualdade de renda na mortalidade do Município de São Paulo / Effect of income inequality in mortality Municipality of Sao Paulo

Alexandre Dias Porto Chiavegatto Filho 30 November 2010 (has links)
Introdução - A maioria dos estudos sobre a teoria da renda relativa tem encontrado associação estatísticamente significativa entre alta desigualdade de renda e piores condições de saúde em grandes regiões como estados norte-americanos ou países. Por outro lado, análises realizadas em municípios e áreas fora dos EUA tem apresentado resultados no mínimo conflitantes. Os maiores obstáculos para que se atinja consenso na área são a inexistência de elevada desigualdade em regiões menores e a dificuldade de controlar pelo conjunto de variáveis de confusão que podem ter efeito na saúde além da desigualdade de renda. O presente estudo objetiva auxiliar na solução desse problema ao analisar o Município de São Paulo por meio de uma metodologia estatística chamada propensity score matching. Metodologia - A análise abordou os 96 distritos da cidade. Foram incluídas 16 variáveis no modelo para identificar distritos comparáveis. Do total de 96 distritos, 27 foram pareados com algum outro (alguns mais de uma vez), formando 17 pares, dos quais apenas um foi composto por distritos que fazem fronteira entre si. Resultados - Após a aplicação do propensity score matching, distritos mais desiguais apresentaram maior mortalidade geral ajustada por idade (41,58 por 10.000 hab; IC 95por cento : 8,85 73,3 por 10.000 hab). Foram também estatísticamente significativas as diferenças de mortalidade para homicídios (8,57 por 10.000; IC 95por cento : 2,60 14,53), doença isquêmica do coração (5,47 por 10.000; IC 95por cento : 0,76 10,17), aids (3,58 por 10.000; IC 95por cento : 0,58 6,57), doença respiratória (3,56 por 10.000; IC 95por cento : 0,18 6,94) e mortalidade infantil (2,8 por 10.000; IC 95por cento : 0,86 4,74). As dez causas 9 básicas mais frequentes foram responsáveis por 72,3por cento do total da diferença de mortalidade entre os distritos mais e menos desiguais. Conclusões - A metodologia estatística foi eficaz para diminuir as diferenças sociais e demográficas, possibilitando a comparação entre distritos semelhantes. A presença de alta desigualdade de renda no Município de São Paulo permitiu a análise do seu efeito na mortalidade / Introduction - The majority of studies on the relative income theory has detected statistically significant associations between high income inequality and worse health conditions for larger areas such as countries or USA states. Nevertheless, for smaller areas such as municipalities or regions outside the USA, the results have been, at best, mixed. The biggest hindrances to a consensus are the lack of high inequalities within smaller areas and the difficulty to control for the many variables that may also affect health beyond the effect of income inequality. This analysis aims to help to solve these problems by applying a statistical analysis known as propensity score matching and by focusing on a very diverse and unequal city such as São Paulo. Methodology - The analysis was done for the 96 distritos of the Municipality of São Paulo, Brazil. The statistical model included 16 variables to account for local heterogeneity. Of the 96 distritos, 27 were matched with a similar one (sometimes, more than once), making a total of 17 pairs (of those, only one pair was made out of two bordering distritos). Results - After the propensity score matching approach, higher inequality distritos had higher age-adjusted overall mortality rate (41.58 per 10,000, 95per cent CI: 8.85 73.3). The difference between high and low inequality was also statistically significant for homicide (8.57 per 10,000; 95per cent CI: 2.60 14.53), ischemic heart disease (5.47 per 10,000; 95per cent CI: 0.76 10.17), HIV/AIDS (3.58 per 10,000; 95per cent CI: 0.58 6.57), respiratory diseases (3.56 per 10,000; 95per cent CI: 0.18 6.94) and infant mortality (2.8 per 10,000; 95per cent CI: 0.86 4.74). The ten most common causes of death accounted for 72.3per cent of total difference in mortality. 11 Conclusion - The statistical methodology was effective to control for local social and demographic heterogeneity, allowing the comparison of only similar distritos. The use of a large and diverse city such as São Paulo made it possible to analyze the effects of income inequality on health
14

Efeito da desigualdade de renda na mortalidade do Município de São Paulo / Effect of income inequality in mortality Municipality of Sao Paulo

Chiavegatto Filho, Alexandre Dias Porto 30 November 2010 (has links)
Introdução - A maioria dos estudos sobre a teoria da renda relativa tem encontrado associação estatísticamente significativa entre alta desigualdade de renda e piores condições de saúde em grandes regiões como estados norte-americanos ou países. Por outro lado, análises realizadas em municípios e áreas fora dos EUA tem apresentado resultados no mínimo conflitantes. Os maiores obstáculos para que se atinja consenso na área são a inexistência de elevada desigualdade em regiões menores e a dificuldade de controlar pelo conjunto de variáveis de confusão que podem ter efeito na saúde além da desigualdade de renda. O presente estudo objetiva auxiliar na solução desse problema ao analisar o Município de São Paulo por meio de uma metodologia estatística chamada propensity score matching. Metodologia - A análise abordou os 96 distritos da cidade. Foram incluídas 16 variáveis no modelo para identificar distritos comparáveis. Do total de 96 distritos, 27 foram pareados com algum outro (alguns mais de uma vez), formando 17 pares, dos quais apenas um foi composto por distritos que fazem fronteira entre si. Resultados - Após a aplicação do propensity score matching, distritos mais desiguais apresentaram maior mortalidade geral ajustada por idade (41,58 por 10.000 hab; IC 95por cento : 8,85 73,3 por 10.000 hab). Foram também estatísticamente significativas as diferenças de mortalidade para homicídios (8,57 por 10.000; IC 95por cento : 2,60 14,53), doença isquêmica do coração (5,47 por 10.000; IC 95por cento : 0,76 10,17), aids (3,58 por 10.000; IC 95por cento : 0,58 6,57), doença respiratória (3,56 por 10.000; IC 95por cento : 0,18 6,94) e mortalidade infantil (2,8 por 10.000; IC 95por cento : 0,86 4,74). As dez causas 9 básicas mais frequentes foram responsáveis por 72,3por cento do total da diferença de mortalidade entre os distritos mais e menos desiguais. Conclusões - A metodologia estatística foi eficaz para diminuir as diferenças sociais e demográficas, possibilitando a comparação entre distritos semelhantes. A presença de alta desigualdade de renda no Município de São Paulo permitiu a análise do seu efeito na mortalidade / Introduction - The majority of studies on the relative income theory has detected statistically significant associations between high income inequality and worse health conditions for larger areas such as countries or USA states. Nevertheless, for smaller areas such as municipalities or regions outside the USA, the results have been, at best, mixed. The biggest hindrances to a consensus are the lack of high inequalities within smaller areas and the difficulty to control for the many variables that may also affect health beyond the effect of income inequality. This analysis aims to help to solve these problems by applying a statistical analysis known as propensity score matching and by focusing on a very diverse and unequal city such as São Paulo. Methodology - The analysis was done for the 96 distritos of the Municipality of São Paulo, Brazil. The statistical model included 16 variables to account for local heterogeneity. Of the 96 distritos, 27 were matched with a similar one (sometimes, more than once), making a total of 17 pairs (of those, only one pair was made out of two bordering distritos). Results - After the propensity score matching approach, higher inequality distritos had higher age-adjusted overall mortality rate (41.58 per 10,000, 95per cent CI: 8.85 73.3). The difference between high and low inequality was also statistically significant for homicide (8.57 per 10,000; 95per cent CI: 2.60 14.53), ischemic heart disease (5.47 per 10,000; 95per cent CI: 0.76 10.17), HIV/AIDS (3.58 per 10,000; 95per cent CI: 0.58 6.57), respiratory diseases (3.56 per 10,000; 95per cent CI: 0.18 6.94) and infant mortality (2.8 per 10,000; 95per cent CI: 0.86 4.74). The ten most common causes of death accounted for 72.3per cent of total difference in mortality. 11 Conclusion - The statistical methodology was effective to control for local social and demographic heterogeneity, allowing the comparison of only similar distritos. The use of a large and diverse city such as São Paulo made it possible to analyze the effects of income inequality on health
15

Développement d'une nouvelle mesure d'équilibre pour l'aide à la sélection des variables dans un modèle de score de propension / Development of a new weighted balance measure to help to select the variables to be included in a propensity score model

Caruana, Emmanuel 01 March 2017 (has links)
Le score de propension s'est progressivement imposé comme l’une des méthodes de référence dans l'analyse des données observationnelles afin de prendre en compte le biais potentiel lié à l’existence de facteurs de confusion dans l'estimation de l'effet du traitement sur le critère de jugement. Parmi les recommandations de bonnes pratiques d'utilisation, le processus de sélection des variables à inclure dans le score final utilisé est essentiel, ainsi que l'évaluation de l'équilibre obtenu sur les covariables après appariement ou pondération sur ce score. Dans l'objectif de prioriser l'inclusion et l'équilibre des variables ayant une relation avec le critère de jugement une nouvelle mesure d'équilibre est proposée dans ce travail de thèse. Une première partie de ce travail a eu pour objectif de développer une mesure globale pondérée permettant d'évaluer l'équilibre global des covariables obtenu après appariement et ainsi d'aider à la sélection d’un modèle de propension le plus parcimonieux possible, en éliminant notamment les variables instrumentales. En effet ces variables ne doivent pas être introduites dans le modèle de score de propension au risque de majorer le biais final d'estimation. Lors des étapes d'évaluation de l'équilibre final obtenu, les différentes mesures d'équilibres disponibles ne prennent le plus souvent pas en compte cette information et concluent souvent à l'intérêt d'inclure une telle variable afin de réduire au maximum le déséquilibre entre les groupes. L'évaluation des performances de cette mesure a dans un premier temps fait appel à des simulations de type Monte Carlo. Dans une seconde partie, une mise en application sur des données réelles issues de la médecine d'urgence a permis de préciser la pratique d'utilisation d'une telle mesure / Propensity score (PS) methods have become increasingly used to analyze observational data and take into account confusion bias in final estimate of treatment effects. The goal of the PS is to balance the distribution of potential confounders across treatment groups. The performance of the PS strongly relies on variable selection in PS construction and balance assessment in PS analysis. Specifically, the choice of the variables to be included in the PS model is of paramount importance. In order to priorize inclusion and balance of variables related to the outcome, a new balance measure was proposed in this thesis. First, a new weighted balance measure was studied to help in construction of PS model and to obtain the most parsimonious model, by excluding instrumental variables known to be related with increasing bias in final treatment estimate. Several balances measures are proposed to assess final balance, but none of them help researchers to not include instrumental variables. We propose a new weighted balance measure that takes into account, for each covariate, its strength of association with the outcome. This measure was evaluated using a simulation study to assess whether minimization of the measure coincided with minimally biased estimates. Secondly, we propose to apply this measure to a real data set from an observational cohort study.
16

A causal analysis of conservation practices on corn yield:evidence from the Mississippi Delta and Arkansas Delta

Pinamang, Melody Afrane 07 August 2020 (has links)
Employing the causal inference methods (matching for binary and continuous treatments), I examined the impact of conservation payments on corn yield. I used the propensity score and covariate distance matching and generalized propensity score methods to manage the problem of selection bias since the enrollment of conservation programs (i.e., receiving conservation payments) is not a randomized experiment. Using USDA Economic Research Service – Agricultural Resource Management Survey (ERS-ARMS) field-level data, I assessed whether receiving conservation payments had harm on corn yield in the Mississippi and Arkansas Delta. The findings from the two binary matchings showed that receiving conservation payments didn’t decrease corn yield. The generalized propensity approach revealed that lower conservation payments received held higher corn yield while higher conservation payments led to lower corn yield.
17

Propensity Score Analysis of Exposure Effects for Spatially Correlated Data

Ou, Ju-Chi 14 June 2010 (has links)
No description available.
18

Diabetes care among elderly medicare beneficiaries with Parkinson's disease and diabetes

Bhattacharjee, Sandipan, Sambamoorthi, Usha January 2015 (has links)
BACKGROUND: Elderly individuals with type 2 diabetes mellitus (T2DM) suffer from several comorbidities, which affect their health outcomes, as well as process of care. This study assessed process and intermediate clinical outcomes of diabetes care among elderly individuals with T2DM and co-occurring Parkinson's disease(PD). METHODS: This study used a retrospective cohort design with propensity score matching using Humana Medicare Advantage Part D claims database (2007-2011) and included elderly (age ≥ 65 years) Medicare beneficiaries with T2DM (identified by ICD-9-CM code of 250.x0 or 250.x2). PD was identified using ICD-9-CM code of 332.xx. After propensity score matching there were 2,703 individuals with T2DM and PD and 8,109 with T2DM and no PD. The three processes of care measures used in this study included: (i) HbA1c test; (ii) Lipid test; (iii) and Nephropathy screening. Intermediate clinical outcomes consisted of glycemic and lipid control. RESULTS: Multivariable conditional logistic regressions revealed that elderly individuals with T2DM and PD were 12 % (AOR: 0.88, 95 %CI: 0.79-0.97) and 18 % (AOR: 0.82, 95 %CI: 0.72-0.94) less likely to meet the annual American Diabetes Association (ADA) recommended HbA1c and lipid testing goals respectively compared to individuals with T2DM and no PD. Multinomial conditional logistic regressions showed that elderly individuals with T2DM and PD were more likely to have HbA1c and lipid (HbA1c < 8 %; LDL-C <100 mg/dl; HDL-C ≥ 50 mg/dl; triglyceride <150 mg/dl; and total cholesterol <200 mg/dl) control. CONCLUSIONS: Among elderly individuals with T2DM, those with PD were less likely to achieve ADA recommended annual HbA1c and lipid testing compared to those without PD. However, PD individuals were more likely to achieve intermediate glycemic and lipid control.
19

The impact of family composition on adult earnings

Skog, Frida January 2016 (has links)
This thesis addresses to what extent childhood family composition – the number of siblings and whether the parents live together, or whether there are non-parental adults and/or half-siblings in the household or not – contributes to variations in adult earnings. The theoretical perspective suggests that resources mediate the effect. While research has shown that siblings, as well as divorce and remarriage, are negatively linked to child outcomes, there are inconsistencies in previous literature. There has been debate over the unconfoundedness of previous studies, something that is handled here by analyzing large sets of representative data using a robust parameter. The longitudinal dataset used is based on Swedish administrative data and the cohorts analyzed are born in the beginning of the 1970s. The data structure is well suited for the assumptions underlying the semi-parametric method propensity score matching. The findings show that family size impacts on adult earnings. However, this is not always of concern. For example, no effect of siblings is found in affluent families, and if siblings are closely spaced this results in better outcomes for children. Divorce and remarriage do not seem to lower the future earnings of children. Thus, this thesis shows that some of the most well-established patterns in the sociology of the family, namely the link between number of siblings and adult earnings, and between divorce/family re-formation and adult earnings, can be broken by resources.
20

Modelagem de propensão ao atrito no setor de telecomunicações / Modeling Attrition Propensity in the Telecommunication Sector

Arruda, Rodolfo Augusto da Silva 12 March 2019 (has links)
A satisfação dos clientes é fundamental para a manutenção do relacionamento com a empresa. Quando eles precisam resolver algum problema, a empresa necessita proporcionar bom atendimento e ter capacidade de resolutividade. No entanto, o atendimento massificado, muitas vezes, impossibilita soluções sensíveis às necessidades dos clientes. A metodologia estatística pode ajudar a empresa na priorização de clientes com perfil a reclamar em um órgão de defesa ao consumidor (ODC), evitando assim uma situação de atrito. Neste projeto, foi realizada a modelagem do comportamento do cliente com relação à propensão ao atrito. Foram testadas as técnicas de Regressão Logística, Random Forest e Algoritmos Genéticos. Os resultados mostraram que os Algoritmos Genéticos são uma boa opção para tornar o modelo mais simples (parcimonioso), sem perda de performance, e que o Random Forest possibilitou ganho de performance, porém torna o modelo mais complexo, tanto do ponto de vista computacional quanto prático no que tange à implantação em sistemas de produção da empresa. / Customer satisfaction is key to maintaining the relationship with the company. When these need to solve some problem, the company needs to provide good service and have resolving capacity. However, the mass service often makes it impossible. The statistical methodology can help the company in the prioritization of clients with profile to complain in ODC, thus avoiding a situation of attrition. In this project was carried out the modeling of the behavior of the client in relation to the propensity to attrition. Logistic Regression, Random Forest and Genetic Algorithms were tested. The results showed that the Genetic Algorithms are a good option to make the model simpler (parsimonious) without loss of performance and that Random Forest allowed performance gain, but it makes the model more complex, both from the point of view computational and practical in relation to the implantation in production systems of the company.

Page generated in 0.4829 seconds