Sökning: "missing data mechanism"

Visar resultat 1 - 5 av 30 avhandlingar innehållade orden missing data mechanism.

  1. 1. Methodology for Handling Missing Data in Nonlinear Mixed Effects Modelling

    Författare :Åsa M. Johansson; Mats O. Karlsson; Andrew C. Hooker; Leon Aarons; Uppsala universitet; []
    Nyckelord :MEDICIN OCH HÄLSOVETENSKAP; MEDICAL AND HEALTH SCIENCES; Pharmacometrics; population models; censored observations; missing covariates; missing dependent variable; missing data mechanism; missing completely at random MCAR ; missing at random MAR ; missing not at random MNAR ; estimation algorithms; Pharmaceutical Science; Farmaceutisk vetenskap;

    Sammanfattning : To obtain a better understanding of the pharmacokinetic and/or pharmacodynamic characteristics of an investigated treatment, clinical data is often analysed with nonlinear mixed effects modelling. The developed models can be used to design future clinical trials or to guide individualised drug treatment. LÄS MER

  3. 2. Uncertainty intervals and sensitivity analysis for missing data

    Författare :Minna Genbäck; Xavier de Luna; Elena Stanghellini; Arvid Sjölander; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; missing data; missing not at random; non-ignorable; set identification; uncertainty intervals; sensitivity analysis; self reported health; average causal effect; average causal effect on the treated; mixed-effects models; Statistics; statistik;

    Sammanfattning : In this thesis we develop methods for dealing with missing data in a univariate response variable when estimating regression parameters. Missing outcome data is a problem in a number of applications, one of which is follow-up studies. LÄS MER

  4. 3. Prostate cancer incidence, treatment and mortality : Empirical longitudinal register-based studies and methods for handling missing data

    Författare :Marcus Westerberg; Rolf Larsson; Hans Garmo; Pär Stattin; Jimmy Olsson; Uppsala universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; statistics; mathematics; prostate cancer; missing data; survival analysis; longitudinal models; incidence; treatment; mortality; Mathematical Statistics; Matematisk statistik; Statistics; Statistik; Urologi; Urology; Epidemiologi; Epidemiology;

    Sammanfattning : The diagnostic activity for prostate cancer has increased substantially in Sweden, primarily due to increased use of prostate-specific antigen (PSA) testing in asymptomatic men, and this has led to a large increase in diagnoses. There have also been changes in the diagnostic workup, guidelines, treatment strategies, and more effective treatments have been introduced in different phases of the disease. LÄS MER

  5. 4. The missing links : Towards an Informed Substitution of Durable Water Repellent Chemicals for Textiles

    Författare :Steffen Schellenberger; Ian Cousins; Stefan Stolte; Stockholms universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Applied Environmental Science; tillämpad miljövetenskap;

    Sammanfattning : Durable water repellents (DWRs) that provide liquid repellency to functional textiles are part of an ongoing global substitution process. The process of substitution was initiated after DWRs based on side-chain fluorinated polymers (long-chain SFPs) were identified to contribute to the diffuse release of long-chain perfluoroalkyl acids (PFAAs) to the environment. LÄS MER

  7. 5. Finding fitness : empirical and theoretical explorations of inferring fitness effects from population-level SNP data

    Författare :Bea Angelica Andersson; Xiao-Ru Wang; Åke Brännström; Tanja Slotte; Umeå universitet; []
    Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; distribution of fitness effects; site frequency spectra; missing data filtering; downsampling; imputation; sample size; population structure; inbreeding; selfing; homozygosity; Arabidopsis; Pinus; DFE-alpha; SLiM; population genomics; adaptation; biology; biologi; evolutionär genetik; evolutionary genetics; populationsbiologi; Population Biology; molekylärbiologi; Molecular Biology; Genetics; genetik;

    Sammanfattning : The distribution of fitness effects (DFE) describes the likelihood that a new mutation has a specific effect on the fitness of an individual in a given population. The shape of the DFE is a result of several factors such as population size, mating system and selective environment, and can in turn influence the evolutionary potential of a species. LÄS MER