Question

Blood glucose levels are used to determine the presence of diabetes. Suppose the mean ln (blood glucose) concentration (mg/dl) in 20 to 32 year olds is 5.00 with a standard deviation of 0.45. A study of 100 people in this age group is planned to test whether they have a different level of plasma glucose than the general population.

a. If the expected difference is 0.15 ln units, what is the probability of rejecting the null hypothesis using a two sided test at a 5% level of significance?

b. How many people would need to be studied to have 90% power under the assumptions in part (a)?

Answer 1

Concentration in 20 to 32 years olds has a standard deviation

a)

Test statistic :

the probability of rejecting the null hypothesis using a two-sided test is : The P-value for the two-tailed test is = 0.0009

b) power of the test is

190 people would be need to study to have 90% power