Statistical Sciences 2244A/B Chapter Notes - Chapter 7: Dont, Confounding, Longitudinal Study
14 Oct 2016
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Observational study: observes individuals and measures variables of interest but does not attempt to influence the responses. The purpose is to describe and compare existing groups or situations: good for things from the heights of adult americans to behaviour of wild animals, poor way to gauge the effect of an intervention. To see response to a change, we have to impose some sort of change. Experiment: deliberately imposes some treatment on individuals in order to observe their responses: the purpose is to study whether the treatment causes a change in response. The difference between these two is important to understand ideas in statistics. Sample - the part of population from which we actually collect information. We use this to draw conclusions about the entire population. To obtain a proper sample design, find exactly what population we want to describe and what we want to measure: give definitions to variables.
