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Informative random censoring survival data are often seen in clinical trials. However, the methodology to deal with this kind of data has not been well developed due to difficulty of identifying the information. Several methods were proposed, for example, by citet{Sia1}. We use simulation studies to investigate sensitivity of these methods and show that the maximum likelihood estimation (MLE) method provides narrower confidence intervals than citet{Sia1}. This is true and expected under the same assumption as in citet{Sia1}. However, we were able to give practical guidelines on how to guess at the missing information of random censoring. We give conditions to obtain more precise estimators for survival data analyses, providing a user-friendly R program. Two real-life data sets are used to illustrate the application of this methodology. / Biostatistics

This dissertation, in its most general context, is an investigation into the modeling of markets with imperfectly informed agents. In such markets, there will invariably be incentives for informed agents to take advantage of information asymmetries by disseminating the relevant information to uninformed agents. Similarly, there will be incentives for uniformed agents to reduce the adverse effects of information asymmetries by acquiring the relevant information. The primary purpose of this dissertation is to demonstrate that the understanding of such markets can be greatly enhanced by explicit modeling both channels of information flow as omitting either channel could eliminate important interaction effects. The arguments in this dissertation are narrowly framed within a familiar differentiated market in which firms advertise and each consumer is imperfectly informed about which product is most suited to his taste. However, the conclusions drawn in the dissertation are applicable to more general economic systems in which it is costly for agents to acquire information relevant to the decision-making process. There is a long-standing debate in the literature about whether or not advertising is purely informative. Although there is extensive research on advertising models and consumer search models, little is known about differentiated markets in which firms advertise and consumers search. In modeling advertising and consumer search, this dissertation questions the relevance of two pieces of evidence that have been offered against the view that advertising is informative. In the first instance, I demonstrate that firms may use purely informative advertising and still maintain market power in the long-run in monopolistically competitive markets; this finding thus rejects the argument that firms rely on manipulating consumer preferences in order to maintain market power in these markets. In the second instance, I demonstrate that advertisements without any information about the product being advertised may still be informative to some consumers; this finding thus rejects the argument that the widespread use of uninformative television advertisements is inconsistent with the view that advertising is informative in nature. This dissertation shows that our understanding of the nature of advertising (information dissemination mechanism) is greatly enhanced by modeling consumer search (information acquisition mechanism).

In the past few years, biomarkers such as progression free survival (PFS) and time to progression (TTP), have been increasingly used as surrogate endpoints for overall survival (OS) in clinical trials in oncology. An issue occurs when clinical trials which demonstrated statistically significant treatment effect for the surrogate marker, shows no significant effect on the true outcome of interest, OS. It is possible that this lack of concordant results was due to informative censoring. Although it is known that informative censoring may bias the observed results, it is not clear what impact informative censoring has on the surrogacy of one marker in relation to a true outcome. In this thesis, we investigated how informative censoring could affect the results of a surrogate endpoint, and how would that affect the surrogacy of that endpoint. A simulation study was conducted to evaluate the impact of informative censoring on the treatment effect on TTP and the outcomes of the surrogate validation methods relative effect (RE), surrogate threshold effect (STE), and the difference between the treatment effect on TTP and on OS (IRE). The results of the simulation showed that having informative censoring for TTP will indeed bias the treatment effect on TTP as well as the results for the validation methods, RE, STE, and IRE. Hence, we conclude that the effect of informative censoring can greatly influence the ability to validate a surrogate marker, and additionally can bias the ability to determine the efficacy of a new therapy from a clinical trial using a surrogate marker as the primary outcome. / Thesis / Master of Science (MSc)

Microarrays measure the abundance of DNA transcripts for thousands of gene sequences, simultaneously facilitating genomic comparisons across tissue types or disease status. These experiments are used to understand fundamental aspects of growth and development and to explore the underlying genetic causes of many diseases. The data from most microarray studies are found in open-access online databases. Bayesian models are ideal for the analysis of microarray data because of their ability to integrate prior information; however, most current Bayesian analyses use empirical or flat priors. We present a Perl script to build an informative prior by mining online databases for similar microarray experiments. Four prior distributions are investigated: a power prior including information from multiple previous experiments, an informative prior using information from one previous experiment, an empirically estimated prior, and a flat prior. The method is illustrated with a two-sample experiment to determine the preferential regulation of genes by tamoxifen in breast cancer cells.

We study an informative path planning problem where the goal is to minimize the time required to learn a spatial field. Specifically, our goal is to ensure that the mean square error between the learned and actual fields is below a predefined value. We study three versions of the problem. In the placement version, the objective is to minimize the number of measurement locations. In the mobile robot version, we seek to minimize the total time required to visit and collect measurements from the measurement locations. A multi-robot version is studied as well where the objective is to minimize the time required by the last robot to return back to a common starting location called depot. By exploiting the properties of Gaussian Process regression, we present constant-factor approximation algorithms that ensure the required guarantees. In addition to the theoretical results, we also compare the empirical performance using a real-world dataset with other baseline strategies. / M. S. / We solve the problem of measuring a physical phenomenon accurately using a team of robots in minimum time. Examples of such phenomena include the amount of nitrogen present in the soil within a farm and concentration of harmful chemicals in a water body etc. Knowing accurately the extent of such quantities is important for a variety of economic and environmental reasons. For example, knowing the content of various nutrients in the soil within a farm can help the farmers to improve the yield and reduce the application of fertilizers, the concentration of certain chemicals inside a water body may affect the marine life in various ways. In this thesis, we present several algorithms which can help robots to be deployed efficiently to quantify such phenomena accurately. Traditionally, robots had to be teleoperated. The algorithms proposed in this thesis enable robots to work more autonomously.

Este estudo teve por objetivo avaliar a eficácia de determinado impresso na fixação dec conhecimentos e adoção de práticas de saúde. Para se atingir esse objetivo foi elaborado o Manual \"Gestante Cardíaca\" para educação de pacientes do Programa \"Cardiopatia e Gravidez\" do Instituto \"Dante Pazzanese\"de Cardiologia. As gestantes cardíacas inscritas no Programa foram divididas em dois grupos. Após consulta médica onde receberam orientação, um dos grupos recebeu o Manual. Conhecimentos e práticas das gestantes foram testados quando ingressaram no Programa e retestados na última consulta. As gestantes do grupo que recebeu o impresso tiveram maior ganho em conhecimentos (82,4 por cento ) e adotaram mais priticas (94,4 por cento ) que as do outro grupo (2,0 por cento e 40,5 por cento ). Os resultados obtidos parecem sugerir a eficácia do Manual para fixar conhecimentos e estimular a gestante cárdiaca na adoção das práticas recomendadas. O processo de elaboraçio do Manual é descrito no trabalho. / The purpose of this study was to evaluate the efficacy of a printed material to reinforce knowledge and in the adoption of health practices. A manual designed to cardiac pregnant women of the Program \"Cardiopathy and Pregnancy\" of the Institute of Cardiology \"Dante Pazzanese\" of São Paulo was prepared. The women were divided into two groups, one of which received the Manual after medical consultation. Both groups were subjected to orientation. Womens\' knowledge and practices were tested at the first consultation and retested at the last one. The group of women who had rcceived the material gained more in knowledge (82,4 per cent ) and adopted more practices (94,4 per cent ) than the group who did not receive the Manual (2,0 per cent and 40,5 per cent ). The results obtained suggest the efficacy of the printed material to reinforce knowledge and stimulate recommended practices. The Manual elaboration process is described in this paper.

Este estudo teve por objetivo avaliar a eficácia de determinado impresso na fixação dec conhecimentos e adoção de práticas de saúde. Para se atingir esse objetivo foi elaborado o Manual \"Gestante Cardíaca\" para educação de pacientes do Programa \"Cardiopatia e Gravidez\" do Instituto \"Dante Pazzanese\"de Cardiologia. As gestantes cardíacas inscritas no Programa foram divididas em dois grupos. Após consulta médica onde receberam orientação, um dos grupos recebeu o Manual. Conhecimentos e práticas das gestantes foram testados quando ingressaram no Programa e retestados na última consulta. As gestantes do grupo que recebeu o impresso tiveram maior ganho em conhecimentos (82,4 por cento ) e adotaram mais priticas (94,4 por cento ) que as do outro grupo (2,0 por cento e 40,5 por cento ). Os resultados obtidos parecem sugerir a eficácia do Manual para fixar conhecimentos e estimular a gestante cárdiaca na adoção das práticas recomendadas. O processo de elaboraçio do Manual é descrito no trabalho. / The purpose of this study was to evaluate the efficacy of a printed material to reinforce knowledge and in the adoption of health practices. A manual designed to cardiac pregnant women of the Program \"Cardiopathy and Pregnancy\" of the Institute of Cardiology \"Dante Pazzanese\" of São Paulo was prepared. The women were divided into two groups, one of which received the Manual after medical consultation. Both groups were subjected to orientation. Womens\' knowledge and practices were tested at the first consultation and retested at the last one. The group of women who had rcceived the material gained more in knowledge (82,4 per cent ) and adopted more practices (94,4 per cent ) than the group who did not receive the Manual (2,0 per cent and 40,5 per cent ). The results obtained suggest the efficacy of the printed material to reinforce knowledge and stimulate recommended practices. The Manual elaboration process is described in this paper.

<p>Arbetet har bestått i att utföra en informativ webguide över en anläggning i Västerås som tillverkar biogas och biogödsel av matrester. Beställaren heter VafabMiljö. Mina kontaktpersoner, Caroline Eklöv och Åsa Lindén, är skolinformatörer. Guiden ska publiceras på VafabMiljös hemsida för skolklasser på Internet och där fungera som en förlängning av informatörernas arbete i skolorna. Målgruppen är barn i årskurs 3-5. En uttalad förebild fanns: Göteborgsföretaget Gryaabs guide om vattenrening Vart tar bajset vägen? (http://www.gryaab.se/).</p><p> </p><p>Under arbetets gång har design- och funktionsbesluten fattats med stöd av:</p><ul type="square"><li>Intervju med kund och besök på anläggningen</li><li>Omvärldsanalys, mestadels på Internet</li><li>Egna erfarenheter</li><li>Kontinuerliga utprovningar</li><li>Litteratur</li></ul><p> </p><p>Arbetet har utförts i Illustrator och Adobe Flash.</p><p> </p><p>Eftersom det var många delar i processen som skulle illustreras var det nödvändigt att arbeta snabbt. Önskemål från kunden var att låta enkelt, tydligt och roligt gå före korrekt återgivning. Detta har lett till ett manér där jag använt mig mer av symboler än verklighetstrogen avbildning. I rapporten beskrivs intressanta designbeslut där min målsättning varit att låta begriplighet gå före realism.</p>

The search for genetic regions associated with complex diseases, such as cancer or Alzheimer's disease, is an important challenge that may lead to better diagnosis and treatment. The existence of millions of DNA variations, primarily single nucleotide polymorphisms (SNPs), may allow the fine dissection of such associations. However, studies seeking disease association are limited by the cost of genotyping SNPs. Therefore, it is essential to find a small subset of informative SNPs (tag SNPs) that may be used as good representatives of the rest of the SNPs. Several informative SNP selection methods have been developed. Our experiments compare favorably to all the prediction and statistical methods by selecting the least number of informative SNPs. We proposed algorithms for faster prediction which yielded acceptable trade off. We validated our results using the k-fold test and its many variations.