I have used the Sample Size Calculator to determine the sample size for my ACBC-study (https://www.sawtoothsoftware.com/support/knowledge-base/general-issues/1544-sample-size-calculator-2
The values I entered are:
Marging of error = 5%
Population size = 20000
According to the Sample Size Calculator the recommended sample size should be 318.
However, when I do the calculation I obtain another recommended sample size which is 147. My calculation is as follows:
x= Z*(c/100)^2 * r * (100-r) = 1.96 * (95/100)^2 * 30 * (100-30)=3714.69
n = (N*x) / ( (N-1) * E^2 + x) = (20000*3714.69) / ((19999)*5^2+ 3714.69) = 147.499
Therefore, may I ask where I did wrong in my calculation?