Question

A researcher wishes to estimate the proportion of adults who have​ high-speed Internet access. What size sample should be obtained if she wishes the estimate to be within 0.04 with 95​% confidence if

​(a) she uses a previous estimate of 0.54​?

​(b) she does not use any prior​ estimates?

Answer 1

(a) she uses a previous estimate of 0.54​?

Formula for sample size : n when using previous estimate ; p_g

Given:

E : Margin of error = 0.04

previous estimate ; p_g = 0.54

for 95% confidence level = (100-95)/100 = 0.05

/2 = 0.025

Sample size : n= 596

(b) she does not use any prior​ estimates

Formula for sample size : n when no previous estimates are being used

Sample size : n= 600