part15 - Public Health 6450 Fall 2011 Lynn Eberly and Andy...

Info iconThis preview shows pages 1–6. Sign up to view the full content.

View Full Document Right Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Public Health 6450 Fall 2011 Lynn Eberly and Andy Mugglin Division of Biostatistics School of Public Health University of Minnesota ph6450@biostat.umn.edu Part 15 Review Contexts in Which Comparisons of Binomial Proportions Arise Risk Differences and Relative Risks for Binomial Proportions Odds Ratios for Binomial Proportions Where are we going? Previously: I One-sample hypothesis testing and CIs for H : p = p (Chapter 8.1) I Two-sample hypothesis testing and CIs for H : p 1- p 2 = 0 (Chapter 8.2) Current topics: I Two-by-two tables and study designs for comparing Binomial proportions (not in M,M &C) I Relative risks and odds ratios for comparing Binomial proportions (not in M,M &C) Eberly and Mugglin PubH 6450 Fall 2011 Part 15 2 / 41 Review Contexts in Which Comparisons of Binomial Proportions Arise Risk Differences and Relative Risks for Binomial Proportions Odds Ratios for Binomial Proportions Two-by-Two Tables The data from two-sample Binomial problems (such as those weve seen), with X 1 B ( n 1 , p 1 ) and X 2 B ( n 2 , p 2 ), can be summarized in a table: Success Group Yes No Total 1 X 1 ( a ) n 1- X 1 ( b ) n 1 2 X 2 ( c ) n 2- X 2 ( d ) n 2 We estimate p 1 and p 2 with I p 1 = X 1 / n 1 = a / ( a + b ) (The red letters are a switch in I p 2 = X 2 / n 2 = c / ( c + d ) . notation to match M,M &C) Eberly and Mugglin PubH 6450 Fall 2011 Part 15 3 / 41 Review Contexts in Which Comparisons of Binomial Proportions Arise Risk Differences and Relative Risks for Binomial Proportions Odds Ratios for Binomial Proportions Two-by-Two Tables (contd) I In many public health and medical contexts, we think of the rows as exposure and the columns as disease. I If the n 1 exposed individuals were randomly sampled from the population of exposed persons, and the n 2 unexposed individuals were randomly sampled from the population of unexposed persons, then p 1 = Pr(disease | exposed) estimated with p 1 p 2 = Pr(disease | unexposed) estimated with p 2 I The probability of having the disease is called the risk of disease. In what kinds of study designs do these tables arise? Eberly and Mugglin PubH 6450 Fall 2011 Part 15 4 / 41 Review Contexts in Which Comparisons of Binomial Proportions Arise Risk Differences and Relative Risks for Binomial Proportions Odds Ratios for Binomial Proportions Seat Belt Use and Fatal Accidents Records of accidents in 1998 by the Department of Highway Safety and Motor Vehicles in Florida: Safety Equipment Injury in Use Fatal Nonfatal Total None 1601 162,527 164,128 Seat belt 510 412,368 412,878 Total 2111 574,895 577,006 We are interested in Pr(disease | exposure), specifically in comparing Pr(fatal accident | no seat belt) to Pr(fatal accident | seat belt)....
View Full Document

This note was uploaded on 11/21/2011 for the course PUBH 6450 taught by Professor Andymugglin during the Fall '10 term at Minnesota.

Page1 / 41

part15 - Public Health 6450 Fall 2011 Lynn Eberly and Andy...

This preview shows document pages 1 - 6. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online