COMM 291 Lecture 11: COMM 291 201 - Lecture 11 - Normal distribution and sampling
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Pfxsy ) p ( x - y co. This approximation good when np to and nq > to p ( x . y so ) plzc. Q : what is probability of getting between. This example is turning a discrete random variable into continuous. Where do data come from ? voluntary surveys leg. Internet usually worthless experimental studies actively manipulate variables observational studies secondary sources sit back and watch eg . Examine part of the whole a how representative of the whole thing ? to sample population. If sample not representative then it"s biased . representative is getting. All characteristics of population in the sample . la. 2 samples you get will be different differences between samples is sampling variability or sampling error f mistake matters not population size o o o o. Sample ( srs ) each case has equal chances of being chosen. Stratified random sample split population into groups with similar characteristics then.
