STAB22H3 Lecture Notes - Dont, Gardasil
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STAB22H3 Full Course Notes
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Want to see whether 2 groups are diff, or do they vary by chance main text, p585. N = 161 loc"s in massachussets, using srs. F drivers wore belt >70% of the time, regardless of gender of passenger(s) Out of 4,208 m drivers w/ f passengers, 2777 (66%) wore belts. Out of 2,763 m drivers w/ m passengers, only 1363 (49. 3%) wore belts p586. Know: diff. in prop"s of men wearing sealtbelts from sample. It is not likely that the diff. we obtained is the truth, b/c prop"s will vary from sample to sample. To do this, req. a new ruler: sd of samplign distribution model for diff. in prop"s. The variance of sum or diff. of 2 indep. random var"s is sum of their variances. => aka for indep. random var"s, variances always add (regardless of whether you are adding or subtracting the 2 random var"s) Why does variation increase, despite subtracting two random.
