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Unformatted text preview: 4/7/2010 1 Welcome to BSCI425 Apr. 7, 2010 Announcements Gordis: Chapter 12 22/03/10 1 BSCI425 2010 @ S. Benson Announcements This Week: Chapters 11 and 12 Quiz today Thursday Project Time Test Next week Chapter 14-15, look for on-line quiz Questions?? 22/03/10 BSCI425 2010 @ S. Benson 2 Q1. For which of the following study designs can you NOT directly determine relative risk? 74% 1. Randomized Clinical Trial Phase III 2. Cohort Study 22/03/10 BSCI425 2010 @ S. Benson 3 R a n d o m iz e d C lin ic a l . . C o h o r t S tu d y C a s e-c o n t r o l S t u d y A l o f th e a b o v e 16% 3% 6% 3. Case-control Study 4. All of the above Q2. The Odds ratio can be used as a measure of relative risk if __ ? 65% 1. The sample size is very large 2. There are no confounding factors 22/03/10 BSCI425 2010 @ S. Benson 4 T h e s a m p le s iz . . T h e r e a r e n o c . . T h e p r e v a le n c e . . T h e in c id e n c e . . A n s w e r s 1 a n d . . 6% 0% 24% 6% 3. The prevalence is high 4. The incidence is low 5. Answers 1 and 4 4/7/2010 2 If frequency (a; = exposed with disease) is low then a + b ~ b And equation becomes a/b divided by c/d Relative risk = 75/10000 / 25/10000 = 3 Odd ratio = 75 x 9925 / 25 x 9975 = 2.97 22/03/10 BSCI425 2010 @ S. Benson 5 W/ disease W/O disease Exposed...
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