Sökning: "cox proportional hazard"

Visar resultat 1 - 5 av 59 avhandlingar innehållade orden cox proportional hazard.

1. 1. Essays on the Assumption of Proportional Hazards in Cox Regression

   Författare :Inger Persson; Kenneth Carling; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Informatics; computer and systems science; Proportional hazards; Cox regression; Proportionality assumption; Informatik; data- och systemvetenskap; Informatics; computer and systems science; Informatik; data- och systemvetenskap; statistik; Statistics;

   Sammanfattning : This thesis consists of four papers about the assumption of proportional hazards for the Cox model in survival analysis. The first paper compares the hazard ratio estimated from the Cox model to an exact calculation of the geometric average of the hazard ratio when the underlying assumption of proportional hazards is false, i.e. LÄS MER

3. 2. The Analysis of Duration and Panel Data in Economics

   Författare :Wolfgang Hess; Nationalekonomiska institutionen; []
   Nyckelord :SAMHÄLLSVETENSKAP; SOCIAL SCIENCES; Monetary Exchange Rate Model; Homogeneity Testing; Panel Cointegration; Pooling; Duration of Trade; Unemployment Duration; Proportional Hazards; Unobserved Heterogeneity; Hazard Rate; Discrete-Time Duration Model; Threshold Excess Model;

   Sammanfattning : This thesis is divided into two distinct parts. The first part contains three chapters dealing with the analysis of duration data from an econometric perspective and with application to trade durations. LÄS MER

4. 3. Cost optimization of maintenance scheduling for wind turbines with aging components

   Författare :Quanjiang Yu; Chalmers tekniska högskola; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; Integer linear optimization; Age-based preventive maintenance scheduling; Renewal-reward theorem; Weibull distribution; Combinatorial optimization; Wind turbine maintenance; Virtual replacement; Condition monitoring data; Cox proportional hazards method; Linear programming;

   Sammanfattning : A major part of the wind turbine operation cost is resulted from the maintenance of its components. This thesis deals with the theory, algorithms, and applications concerning minimization of the maintenance cost of wind power turbines, using mathematical modelling to find the optimal schedules of preventive maintenance activities for multi-component systems. LÄS MER

5. 4. Diabetes, metformin and gastric adenocarcinoma

   Författare :Jiaojiao Zheng; Karolinska Institutet; Karolinska Institutet; []
   Nyckelord :;

   Sammanfattning : Diabetes may increase the risk and mortality of certain cancers, but its association with gastric adenocarcinoma is not clear. On the other hand, metformin, a first-line treatment for diabetes, may reduce cancer risks and improve cancer-related survival, but these associations have not been confirmed in gastric adenocarcinoma as well. LÄS MER

7. 5. Cardiovaskular risk factors and complications in type 1 and type 2 diabetes

   Författare :Katarina Eeg-Olofsson; Göteborgs universitet; []
   Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Diabetes; Cardiovascular diseases; Epidemiology;

   Sammanfattning : Patients with diabetes have increased risk of cardiovascular disease (CVD) and mortality compared to the general population. The aim of this work was to describe the clinical characteristics and risk factors in patients with type 1 diabetes, and also to investigate the association between glycaemic control and CVD in type 1 and type 2 diabetes, and to analyse the association between BMI, overweight and obesity, and CVD in type 2 diabetes. LÄS MER