1. Group exercise lecture 8

3. For the previous table What is the probability a patient with HIV has HBV infection (answer using probability notation)? What is the probability a patient with HIV has HBV infection (answer using probability notation)? What is the probability a patient without HIV has HBV infection (answer using probability notation)? What is the probability a patient without HIV has HBV infection (answer using probability notation)? What is the probability a patient has both HIV and HBV? (answer using probability notation)? What is the probability a patient has both HIV and HBV? (answer using probability notation)? Are HIV and HBV independent: hint, use the addition rule Are HIV and HBV independent: hint, use the addition rule

5. In a hypothetical community, 50% of all people smoke and 40% are overweight. The percentage of people who are both overweight and smoke is 30% What % of people smoke, are overweight or have both conditions (construct a 2 x 2 table) What % of people smoke, are overweight or have both conditions (construct a 2 x 2 table) Use your calculations for the above Q and verify the addition rule of probabilities: P(A or B) = P(A)+P(B) - P(A and B) Use your calculations for the above Q and verify the addition rule of probabilities: P(A or B) = P(A)+P(B) - P(A and B) You sample at random a person from this community and find that he or she smokes. What is the probaility that he or she is oveweight? You sample at random a person from this community and find that he or she smokes. What is the probaility that he or she is oveweight? Are smoking and overweight independent? Are smoking and overweight independent?

6. OverweightNot overweight Total Smoker0.30.20.5 Non-smoker0.10.40.5 Total0.40.61

7. A 53 year old man comes in for an influenza vaccine but during the consultation he asks about his risk of a heart attack because of the recent death of a friend. You note from his records that his BP is 160/95 mmHg; he has no diabetes; he smokes 20 cigarettes a day and his total cholesterol is 5.2 mmol/l and his HDL is 0.9 mm/l. A 53 year old man comes in for an influenza vaccine but during the consultation he asks about his risk of a heart attack because of the recent death of a friend. You note from his records that his BP is 160/95 mmHg; he has no diabetes; he smokes 20 cigarettes a day and his total cholesterol is 5.2 mmol/l and his HDL is 0.9 mm/l. Use the cardiovascular risk chart to calculate his 10 year risk of cardiovascular event. Use the cardiovascular risk chart to calculate his 10 year risk of cardiovascular event. What would his risk be if he was a non-smoker? What would his risk be if he was a non-smoker?