POPM 3240 Lecture Notes - Lecture 2: Herd Immunity, Observational Error, Confounding
2 Dec 2017
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(cid:8208) size of a sample will not address bias: types of bias. Spurious associations: fake; correlation does not imply causation. Real associations: true; casual relation or due to confounding factor. Casual pathway/relationships/association: observed association of exposure & disease; exposure develops into disease (simple, straightforward: the exposure can either be , direct causation: factor directly causes a disease/health outcome without steps between, factor disease. Component cause: helps us understand which factors are necessary and/or su ecient. One of a number of factors that, in combination, constitute a su cient cause . Removing one component of a su cient cause will render it insu cient. Other factors in uencing combinations: biological susceptibility, genetics, social determinants, clinical factors, cultural in uence, psychological factors. Koch added: infectious disease cannot be transmitted to animals; the regular (1) & exclusive (2) presence of the organism proves a casual relationship (he denies the third postulate) 3 important issues in determining causality: bias, confounding.
