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Visar resultat 11 - 15 av 1307 avhandlingar som matchar ovanstående sökkriterier.

1. 11. Statistical modeling in international large-scale assessments

   Författare :Inga Laukaityte; Marie Wiberg; Kenny Bränberg; Ewa Rolfsman; Bernard Veldkamp; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; multilevel model; plausible values; sampling weights; missing information; multiple imputation; non-monotone missing pattern; TIMSS; PISA; Statistics; statistik; pedagogik; Education;

   Sammanfattning : This thesis contributes to the area of research based on large-scale educational assessments, focusing on the application of multilevel models. The role of sampling weights, plausible values (response variable imputed multiple times) and imputation methods are demonstrated by simulations and applications to TIMSS (Trends in International Mathematics and Science Study) and PISA (Programme for International Student Assessment) data. LÄS MER

3. 12. Statistical methods for register based studies with applications to stroke

   Författare :Anita Lindmark; Marie Eriksson; Xavier de Luna; Eva-Lotta Glader; Saskia le Cessie; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Registers; quality of care; socioeconomic status; hospital performance; stroke; mediation; sensitivity analysis; truncation; censoring; Statistics; statistik;

   Sammanfattning : This thesis adds to the area of register based research, with a particular focus on health care quality and (in)equality. Contributions are made to the areas of hospital performance benchmarking, mediation analysis, and regression when the outcome variable is limited, with applications related to Riksstroke (the Swedish stroke register). LÄS MER

4. 13. Valid causal inference in high-dimensional and complex settings

   Författare :Niloofar Moosavi; Xavier de Luna; Jenny Häggström; Edward Kennedy; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Causal inference; high dimension; sensitivity analysis; variable selection; convolutional neural network; semiparametric efficiency bound; Statistics; statistik;

   Sammanfattning : The objective of this thesis is to consider some challenges that arise when conducting causal inference based on observational data. High dimensionality can occur when it is necessary to adjust for many covariates, and flexible models must be used to meet convergence assumptions. The latter may require the use of a novel machine learning estimator. LÄS MER

5. 14. Causal inference and case-control studies with applications related to childhood diabetes

   Författare :Emma Persson; Ingeborg Waernbaum; Xavier de Luna; Gisela Dahlquist; Stijn Vansteelandt; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; covariate selection; design-weighted estimation; marginal effect; matching; register study; treatment effect; type 1 diabetes mellitus; Statistics; statistik;

   Sammanfattning : This thesis contributes to the research area of causal inference, where estimation of the effect of a treatment on an outcome of interest is the main objective. Some aspects of the estimation of average causal effects in observational studies in general, and case-control studies in particular, are explored. LÄS MER

7. 15. Extensions of the kernel method of test score equating

   Författare :Gabriel Wallin; Marie Wiberg; Jenny Häggström; Anton A. Béguin; Umeå universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Test equating; Nonequivalent groups; Standard error of equating; bandwidth selection; log-linear models; item response theory; Statistics; statistik;

   Sammanfattning : This thesis makes contributions within the area of test score equating and specifically kernel equating. The first paper of this thesis studies the estimation of the test score distributions needed in kernel equating. LÄS MER