A researcher wishes to estimatethe proportion of adults who

A researcher wishes to estimatethe proportion of adults who have high speed internet acess. What sample size should be obtained if she wishes the estimate to be within 0.03 with 90% confidence if (a) she uses a prvious estimate of 0.58? (b) she does not use any prior estimates.

Solution

a)
Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)
Z a/2 at 0.1 is = 1.64
Samle Proportion = 0.58
ME = 0.03
n = ( 1.64 / 0.03 )^2 * 0.58*0.42
= 727.985 ~ 728

b)
Compute Sample Size ( n ) = n=(Z/E)^2*p*(1-p)
Z a/2 at 0.1 is = 1.64
Samle Proportion = 0.5
ME = 0.03
n = ( 1.64 / 0.03 )^2 * 0.5*0.5
= 747.111 ~ 748