PUBHLTH 1 Lecture Notes - Lecture 6: Clinical Trial, Selection Bias, Bran
Document Summary
Intervention study : subjects may not follow prescribed behavior throughout study period. Cohort study: sometimes hard to isolate which of many factors are responsible for health differences. Case-control study: control group may not be truly comparable; also errors in reporting or recalling. For all studies, must worry about differential dropouts. News reports (oat bran prevent cancer, to make no difference) Media takes only some information from research and takes it out of context, misleading the public. Confounding variables (coffee and smoking w/ pancreatic cancer) Selection bias (heart disease patient, control digestive problems, dietary fat) Reporting bias or recall bias: people who drink heavily underreport consumption. Results of cohort study were confounded by associated factors that made women taking hrt healthier, even without the therapy. Tuskegee syphilis study (to observe people who didn"t receive therapy) New rules - informed consent (participant must sign/consent to experiment) New rules - institutional review boards need to give ok .
