Question: how to calculate 95 confidence interval for binomial distribution?
Answer: where p = proportion of interest. n = sample size. α = desired confidence. z1- α/2 = “z value” for desired level of confidence. z1- α/2 = 1.96 for 95% confidence. z1- α/2 = 2.57 for 99% confidence. z1- α/2 = 3 for 99.73% confidence.