unit 5 additional answers

unit 5 additional answers - Click to edit Master subtitle...

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Unformatted text preview: Click to edit Master subtitle style Unit 5 Questions & Answers Structure of class n Study guide for each unit u Questions/concepts for current unit Time to work on questions Time for Q&A/clarifications, can go back to lecture as necessary u Break u Continue questions/concept as needed u Provide homework questions (on Bb for you to start working on) u Homework answers to be provided Wednesdays (questions on Monday before class) Note about reading assignment  Provides formulae to calculate confidence intervals. EPB students should understand this (will help in more advanced classes) but no CI calculations will be on Epi 6000 exams.  Oleckno discusses AR and calculations – this will be covered later in our course. Overview of study designs Overview of associations: non-directional and uni-directional Think about causal pathways: would like to infer temporal association between E and D Viewing all of epidemiologic methods in context of the prospective cohort study design Experimental (RCT) study design vs. observational prospective cohort study design Prospective, retrospective (historical) cohort and ambi-directional study designs When to choose a cohort design Scale of the RR/OR Selection of the unexposed cohort in cohort studies: internal, external (separate unexposed cohort vs. general population) Healthy worker effect Sources of exposure data Validity and reliability Sources of outcome data Sources of concern in cohort studies Measures of association in cohort studies: risk ratio, rate ratio, SMR, PMR Advantages and disadvantages of the PMR vs. SMR Study guide for Unit 5: Cohort Studies Let’s start with a review of measures of effect: 118 182 207 93 H1N1 flu No H1N1 flu Plane travel within last week (+) No plane travel within last week (-) Case-control study : Calculate point estimate. OR/RR? Cohort study : Calculate point estimate. OR/ RR? What kind of RR? 21 1 38 9 30 30 60 Let’s start with a review of measures of effect: 118 182 207 93 H1N1 flu No H1N1 flu Plane travel ≤ last week No plane travel ≤ last week Case-control study: Calculate point estimate. 1.44 OR/RR? OR Cohort study: Calculate point estimate. 1.19 OR/RR? RR What kind of RR? Risk Ratio 21 1 38 9 30 30 60 Why does the OR overestimate the RR? n Write your answer here. Why does the OR overestimate the RR? u Is the disease rare? Is the flu rare? We may not know the answer to this unless we consult other sources. u Do we know whether there is an unambiguous relation between E and D? (Do we know if E precedes D in time?) Probably yes u Use prevalence ratio (calculated as Risk Ratio) if either one of these conditions is not met (Unit 3) u OR will overestimate the correct point estimate if (a) disease is not rare and (b) there is an ambiguous biologic mechanism or if association is bi-directional What is the difference between an ‘association’ and a ‘causal association’?...
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This note was uploaded on 07/15/2011 for the course PHC 6000 taught by Professor Staff during the Summer '08 term at University of South Florida.

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unit 5 additional answers - Click to edit Master subtitle...

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