Question

how do i get the Z in this statistics equation?
n= ((Za/2 standard deviatoin)/ Error))^2

Answer 1

This the formula to determine a sample size. The data you need is Std Deviation, Error and the info you need to calculate Zalpha/2, that is the confiedence interval. For a confidence level, say, of 95%, then you need to calculate Z score for alpha/2, thus 0.025 [calculated as (1-Confidence level)/2]. Check in tables for normal distribution to get the value

Answer 2

This the formula to determine a sample size. The data you need is Std Deviation, Error and the info you need to calculate Zalpha/2, that is the confiedence interval. For a confidence level, say, of 95%, then you need to calculate Z score for alpha/2, thus 0.025 [calculated as (1-Confidence level)/2]. Check in tables for normal distribution to get the value