MATH 243 Lecture Notes - Lecture 5: Karl Pearson, Simple Random Sample, Sample Space
25 Apr 2017
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Webwork 2 due m @ 5 pm. Sample = part of pop. which we sample. Sampling design = how we choose sample. Convenience sample = sample selected by taking members easiest to reach. Voluntary response sample = responders chose to respond themselves. Biased = design systematically favors one outcome. Simple random sample (srs) = everyone has equal chance of being selected. A political scientist wants to know how college students feel about the social security system. She obtains a list of the 3,456 undergrads @ her college & mails questions to 250 students at random. Observational study = o(cid:271)ser(cid:448)es i(cid:374)di(cid:448)iduals (cid:271)ut does(cid:374)"t atte(cid:373)pt to i(cid:374)flue(cid:374)ce responses. Experiment = deliberately imposes treatment on individuals. Confounded variables = (cid:1006) (cid:448)aria(cid:271)les (cid:449)here respo(cid:374)se (cid:448)aria(cid:271)les (cid:272)a(cid:374)"t (cid:271)e disti(cid:374)guished. Treatment = condition (specific) applied to subjects. Statistically significant = observed effect so large it would rarely occur by chance. Matched pairs design = compares 2 treatments.
