11:709:493 Lecture Notes - Lecture 1: Randomized Controlled Trial, Observational Study, Ecological Study
12 May 2020
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Assigns individuals/groups to interventions/exposures under study: it is possible to make inferences about causation. Examples: observational, ecological, cross-sectional, case-control, cohort (prospective or retrospective, experimental, randomized controlled (clinical) trial, non-randomized trials, natural experiments. Hierarchy of scientific evidence (higher up = better evidence: meta-analysis of rcts, systematic review, randomized control trial, non-randomized studies, cohort studies, case control studies, cross sectional studies, ecological studies. Observational study conducted at a defined point in time with one measurement per unit of analysis. Allows you to estimate the prevalence of a disease: group 1, group 2, group 3 = compared at one time. Advantages: cost-efficient, short duration, easy to implement, ethical. Disadvantages: no temporal (time) information, not suited for rare disease or those with short duration, non-response bias, disease can affect exposure measurement (reverse causation) An observational study where the unit of analysis is populations. It compares exposures and outcomes/diseases across various populations using aggregate data. Nutrition data usually comes from national studies.
