STAB22H3 Lecture Notes - Lecture 17: Observational Study, The Control Group, Statistical Significance
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Stab22 lecture 17 observational studies and experiments: tuesday, october 30th, 2018 week 9, observational study vs. Experiment: observational study, observes individuals and measures variables of interest but does not attempt to influence the response. Independent variable is not under control of researcher: experiment. Looking back : data collected after the events occurred, have to wait after the events happen to do anything, pros/cons, easier to obtain data for rare events, less time consuming, usually more confounding and bias, 2. Control: we control sources of variation other than the factors we are testing by making conditions as similar as possible for all treatment groups, make sure other things that can affect the response are minimized, 2. Randomize: randomize units into treatment groups to equalize for uncontrollable sources of variation, does not eliminate the effects of these sources, but can spread them out across the treatment levels so we can see past them, 3.
