You can use the formula to calculate a sample size for a confidence level of 99 and margin of error -1 01 using the standard deviation suggestion of05. If the population is N then the corrected sample size should be 186N N185. Necessary Sample Size Z-score2 StdDev 1-StdDev margin of error2.
Therefore the sample size can be calculated using the formula as 10000 196 2 05 1-05 005 2 10000 1 196 2 05 1-05 005 2 Therefore 370 customers will be adequate for deriving meaningful inference.
N NX X N 1 where X Z a22 p 1-p MOE 2 and Z a2 is the critical value of the Normal distribution at a2 eg. It all depends on the specific project en the method you are using. Calculation of Sample Size 1201200200. This equation is for an unknown population size or a very large population size.