Statistical Sciences 2244A/B Lecture Notes - Lecture 2: Dependent And Independent Variables
15 Sep 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. o. 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. o. 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. Cofounded: two variables (explanatory variables or lurking variables) are said to be this when their effects on a response variable can not be distinguished from each other. o. Explanatory variables (independent variable): variable that may explain changes in another variable. o.
