Ecological
comparing different places and their geography.
Cross sectional
survey that’s done once during a specific time.
Case control
comparing people with and without disease to find what caused the disease.
Cohort
comparing people with and without exposure to risk factors and see what happened to each.
Randomized controlled trial
human experiment. People get randomly assigned to an experimental or controlled group.
Quasi experiment
human experiment. People get assigned based on a criteria which already exists. Might be assigning subjects based on a case definition.