Suppose you had been in charge of designing the study What s

Suppose you had been in charge of designing the study. What sample size would be needed to construct a margin of error of 2% with 95% confidence? Use the prior point estimate of p*=0.15 for this calculation. Round up to the nearest whole number. (For example, 144.1 would round to 145)

n= ???

Solution

Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)
Z a/2 at 0.05 is = 1.96
Samle Proportion = 0.15
ME = 0.02
n = ( 1.96 / 0.02 )^2 * 0.15*0.85
= 1224.51 ~ 1225