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PH 241: Lecture 4 Nicholas P. Jewell University of California Berkeley January 25-30, 2006. Measures of Association: Relative Risk. Relative measure RR = 1 Independence Note upper bound RR is not symmetric in roles of D and E. Non-Symmetry of RR. 1991 US Infant Mortality.
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PH 241: Lecture 4 Nicholas P. Jewell University of California Berkeley January 25-30, 2006
Measures of Association: Relative Risk • Relative measure • RR = 1 Independence • Note upper bound • RR is not symmetric in roles of D and E
1991 US Infant Mortality RR (assoc. with unmarried) =
Measures of Association: Odds Ratio • Relative measure • OR = 1 Independence • No upper bound • ORis symmetric in roles of D and E
1991 US Infant Mortality OR (assoc. with unmarried)
RH (solid line), RR (dotted line), OR (dash-dotted line) as Risk Period extends in Time
Measures of Association: Odds Ratio • Absolute comparison • ER = 0 Independence • ER is not symmetric in roles of D and E
Measures of Association: Attributable Risk Number of cases with current exposure distribution Number of cases with no exposure to E Population size = N
1991 US Infant Mortality AR (assoc. with unmarried)
Attributable Risk—Caution! • Encourages causal interpretation that may be incorrect • Assumes modification of E doesn’t change other risk factors • "Baseball is 90% mental -- the other half is physical." (Yogi Berra)