986 resultados para Logistic regression methodology


Relevância:

90.00% 90.00%

Publicador:

Resumo:

The problems of combinatory optimization have involved a large number of researchers in search of approximative solutions for them, since it is generally accepted that they are unsolvable in polynomial time. Initially, these solutions were focused on heuristics. Currently, metaheuristics are used more for this task, especially those based on evolutionary algorithms. The two main contributions of this work are: the creation of what is called an -Operon- heuristic, for the construction of the information chains necessary for the implementation of transgenetic (evolutionary) algorithms, mainly using statistical methodology - the Cluster Analysis and the Principal Component Analysis; and the utilization of statistical analyses that are adequate for the evaluation of the performance of the algorithms that are developed to solve these problems. The aim of the Operon is to construct good quality dynamic information chains to promote an -intelligent- search in the space of solutions. The Traveling Salesman Problem (TSP) is intended for applications based on a transgenetic algorithmic known as ProtoG. A strategy is also proposed for the renovation of part of the chromosome population indicated by adopting a minimum limit in the coefficient of variation of the adequation function of the individuals, with calculations based on the population. Statistical methodology is used for the evaluation of the performance of four algorithms, as follows: the proposed ProtoG, two memetic algorithms and a Simulated Annealing algorithm. Three performance analyses of these algorithms are proposed. The first is accomplished through the Logistic Regression, based on the probability of finding an optimal solution for a TSP instance by the algorithm being tested. The second is accomplished through Survival Analysis, based on a probability of the time observed for its execution until an optimal solution is achieved. The third is accomplished by means of a non-parametric Analysis of Variance, considering the Percent Error of the Solution (PES) obtained by the percentage in which the solution found exceeds the best solution available in the literature. Six experiments have been conducted applied to sixty-one instances of Euclidean TSP with sizes of up to 1,655 cities. The first two experiments deal with the adjustments of four parameters used in the ProtoG algorithm in an attempt to improve its performance. The last four have been undertaken to evaluate the performance of the ProtoG in comparison to the three algorithms adopted. For these sixty-one instances, it has been concluded on the grounds of statistical tests that there is evidence that the ProtoG performs better than these three algorithms in fifty instances. In addition, for the thirty-six instances considered in the last three trials in which the performance of the algorithms was evaluated through PES, it was observed that the PES average obtained with the ProtoG was less than 1% in almost half of these instances, having reached the greatest average for one instance of 1,173 cities, with an PES average equal to 3.52%. Therefore, the ProtoG can be considered a competitive algorithm for solving the TSP, since it is not rare in the literature find PESs averages greater than 10% to be reported for instances of this size.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Background: Metabolic Syndrome (MS) is defined as the association of numerous factors that increase cardiovascular risk and diet is one of the main factors related to increase the MS in the population. This study aimed to evaluate the association of diet on the presence of MS in an adult population sample.Methodology: 305 adults were clinically screened to participate in a lifestyle modification program. Anthropometric assessments included waist circumference (WC), body fat and calculated BMI (kg/m(2)) and muscle-mass index (MMI kg/m(2)). Dietary intake was estimated by 24 h dietary recall. Fasting blood was used for biochemical analysis. MS was diagnosed using NCEP-ATPIII (2001) criteria with adaptation for glucose (>= 100 mg/dL). Logistic regression (Odds ratio) was performed in order to determine the odds ratio for developing MS according to dietary intake.Results: An adequate intake of fruits, OR = 0.52 (CI:0.28-0.98), and an intake of more than 8 different items in the diet (variety), OR = 0.31 (CI: 0.12-0.79) showed to be a protective factor against a diagnosis of MS. Saturated fat intake greater than 10% of total caloric value represented a risk for MS diagnosis, OR = 2.0 (1.04-3.84).Conclusion: Regarding the dietary aspect, a risk factor for MS was higher intake of saturated fat, and protective factors were high diet variety and adequate fruit intake.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Objectives. To identify factors associated with death in visceral leishmaniasis (VL) cases. Patients and Methodology. We evaluated prognostic factors for death from VL in São Paulo state, Brazil, from 1999 to 2005. A prognostic study nested in a clinical cohort was carried out by data analysis of 376 medical files. A comparison between VL fatal cases and survivors was performed for clinical, laboratory, and biological features. Association between variables and death was assessed by univariate analysis, and the multiple logistic regression model was used to determine adjusted odds ratio for death, controlling confounding factors. Results. Data analysis identified 53 fatal cases out of 376 patients, between 1999 and 2005 in São Paulo state. Lethality was 14.1 (53/376), being higher in patients older than fifty years. The main causes of death were sepsis, bleeding, liver failure, and cardiotoxicity due to treatment. Variables significantly associated with death were severe anemia, bleeding, heart failure, jaundice, diarrhea, fever for more than sixty days, age older than fifty years, and antibiotic use. Conclusion. Educational health measures are needed for the general population and continuing education programs for health professionals working in the affected areas with the purpose of identifying and treating early cases, thus preventing the disease evolution towards death. © 2012 Geraldine Madalosso et al.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Pós-graduação em Doenças Tropicais - FMB

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Introduction: Given the repercussion of the important role of physical activity in the prevention of sickness and non-communicable diseases / loss, many works have been done in order to understand the association of sociodemographic characteristics with sedentarism. The elements which influence the physical activity practice are countless. Besides the intrapersonal element, environment elements (social environment, cultural environment, public politics, information environment, natural environment etc.) are also important in the life style. Yet, the way that the person understands the environment can be considered in the planning of the strategies to change the sedentary behavior. Objective: Verify the association of the environment perception with the practice of physical activity (FA) at leisure time in adults living in Rio Claro – SP. Methodology: The sample consists of 470 adults, all residente in rio Claro-SP, aged ≥ 18 years old. The chosen participants answered to the questionnaires: Neighborhood Environmental Walkability Scale (NEWS), International Physical Activity (IPAQ) and to a specific questionnaire with personal data (age, sex, educational level, economical level, weight, height and marital status). The analysis of the connection between the variables was done through the Logistic Regression with Confidence Interval of 95%, using the software SPSS 17.0. Those who reached the recommendation of 10 minutes or more of physical activity in leisure time for week were classified as active, and those who did not reach the recommendation were classified as underactive. Results: The proportion of subjects who practiced physical activity in leisure time was 38,7%, and the male subjects, as well as those classified as better social level showed higher chances to practice at least 10 minutes weekly of physical activity during leisure. Still, walking the dog, soccer fields and gardens near the house (less than 10 walking minutes), were...

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Static analysis tools report software defects that may or may not be detected by other verification methods. Two challenges complicating the adoption of these tools are spurious false positive warnings and legitimate warnings that are not acted on. This paper reports automated support to help address these challenges using logistic regression models that predict the foregoing types of warnings from signals in the warnings and implicated code. Because examining many potential signaling factors in large software development settings can be expensive, we use a screening methodology to quickly discard factors with low predictive power and cost-effectively build predictive models. Our empirical evaluation indicates that these models can achieve high accuracy in predicting accurate and actionable static analysis warnings, and suggests that the models are competitive with alternative models built without screening.

Relevância:

90.00% 90.00%

Publicador:

Resumo:

Background: Over the last century the incidence of cutaneous melanoma has increased worldwide, a trend that has also been observed in Brazil. The identified risk factors for melanoma include the pattern of sun exposure, family history, and certain phenotypic features. In addition, the incidence of melanoma might be influenced by ethnicity. Like many countries, Brazil has high immigration rates and consequently a heterogenous population. However, Brazil is unique among such countries in that the ethnic heterogeneity of its population is primarily attributable to admixture. This study aimed to evaluate the contribution of European ethnicity to the risk of cutaneous melanoma in Brazil. Methodology/Principal Findings: We carried out a hospital-based case-control study in the metropolitan area of Sao Paulo, Brazil. We evaluated 424 hospitalized patients (202 melanoma patients and 222 control patients) regarding phenotypic features, sun exposure, and number of grandparents born in Europe. Through multivariate logistic regression analysis, we found the following variables to be independently associated with melanoma: grandparents born in Europe-Spain (OR = 3.01, 95% CI: 1.03-8.77), Italy (OR = 3.47, 95% CI: 1.41-8.57), a Germanic/Slavic country (OR = 3.06, 95% CI: 1.05-8.93), or >= 2 European countries (OR = 2.82, 95% CI: 1.06-7.47); eye color-light brown (OR = 1.99, 95% CI: 1.14-3.84) and green/blue (OR = 4.62; 95% CI 2.22-9.58); pigmented lesion removal (OR = 3.78; 95% CI: 2.21-6.49); no lifetime sunscreen use (OR = 3.08; 95% CI: 1.03-9.22); and lifetime severe sunburn (OR = 1.81; 95% CI: 1.03-3.19). Conclusions: Our results indicate that European ancestry is a risk factor for cutaneous melanoma. Such risk appears to be related not only to skin type, eye color, and tanning capacity but also to others specific characteristics of European populations introduced in the New World by European immigrants.