Question

You are testing a flu vaccine tracking the proportion of people who do not fall ill after using the vaccine and subsequent exposure to the infected individuals. How many people would you need to include in your study if you desire to have a margin of error of three percentage points, and the significance level of 95%?

Answer 1

solution:

confidence level = CL = 0.95

=1 - CL = 1 - 0.95 = 0.05

critical value of at (0.05/2) = 1.96

critical value can be found from the z table

given marging of error E = 3% = 0.03

if proportion is not provided , we assume p = 0.5 to find the appropriate required sample size n

we know that ,

so required sample size for the study = 1067