HLTH 501 WEEK 4 PROBLEMS
HLTH 501 WEEK 4 PROBLEMS—30 POINTS10 ponts per problem.1. The mean body mass index (BMI) for boys age 12 is 23.6. An investigator wants to test ifthe BMI is higher in 12-year-old boys living in New York City. How many boys areneeded to ensure that a two-sided test of hypothesis has 80% power to detect a differencein BMI of 2 units? Assume that the standard deviation in BMI is 5.7. ES ?1 – ? 0? Z1- Zn 1 /2ES 2 = Alpha = ______Z1-?/2= ________Z1-? = ________ES = ________n= ________2. An investigator wants to estimate caffeine consumption in high school students. How manystudents would be required to estimate the proportion of students who consume coffee? Supposewe want the estimate to be within 5% of the true proportion with 95% confidence.Alpha = ________Z= ________p= ________E = ________n= ________ 3. A crossover trial is planned to evaluate the impact of an educational intervention program toreduce alcohol consumption in patients determined to be at risk for alcohol problems. The planis to measure alcohol consumption (the number of drinks on a typical drinking day) before theintervention and then again after participants complete the educational intervention program.How many participants would be required to ensure that a 95% confidence interval for the meandifference in the number of drinks is within 2 drinks of the true mean difference? Assume thatthe standard deviation of the difference in the mean number of drinks is 6.7 drinks.Z= ________s= ________E = ________Page 1 of 2 HLTH 501 n= ________ Page 2 of 2
