gwas and snp数据分析.pptVIP

Statistical Analysis in Case-Control studies Summer International Workshop Aug, 09, Beijing Outline Introduction Basic Statistical Methods of Case-control Study GWAS A Novel Epistasis-testing Procedure Aim of Genetic Studies Dramatic variation do exist within a same spice Almost every biological phenomenon involves a genetic component There is always a keen need for us to seek the genetic variation relates to complex traits. Different Design Strategies Intervention studies Clinic trials Observational studies Case-control studies Cohort studies Cohort Studies A cohort study is a study where a group of individuals are followed. Cohort studies can be either prospective or retrospective Case-Control Studies Case-control studies are used to identify factors that may contribute to a medical condition by comparing subjects who have that condition (the ‘cases’) with patients who do not have the condition but are otherwise similar (the ‘controls’) Case-control studies are retrospective and non-randomized Case-Control Studies Selection of Cases Population-based cases: include all subjects or a random sample of all subjects with the disease at a single point or during a given period of time in the defined population. Hospital-based cases: All patients in a hospital department at a given time Selection of Controls Principles of Control Selection: Study base: Controls can be used to characterise the distribution of exposure Comparable-accuracy: Equal reliability in the information obtained from cases and controls (to avoid systematic misclassification) Overcome confounding: Elimination of confounding through control selection (matching or stratified sampling) Selection of Controls General population controls: registries, households, telephone sampling costly and time consuming recall bias eventually high non-response rate Hospitalised controls: Patients at the same hospital as the cases Easy to identify; less recall bias; higher response rate C