In a recent poll, 350 people were asked if they liked dogs, and 52% said they did. Find the margin of error of this poll, at the 99% confidence level. Give your answer to three decimals

Answer 1

margin of error = z-critical for 99% confidence level * standard error

sample proportion = 0.52 (phat)

sample size = 350 (n)

standard error = sqrt(0.52*0.48/350) = 0.027

z-critical for 99% CL = z-score for 0.995 probability (as 99% CI is middle 99%, leaving 0.05 at each tail): 2.58

margin of error = 2.58 * 0.027 = 0.07