Getting The Sample Size Formula. Necessary Sample Size Z-score2 StdDev1-StdDev margin of error2 Here is how the math works assuming you chose a 95 confidence level 5 standard deviation and a margin of error confidence interval of - 5. In calculating the sample size we are interested in calculating the population parameter.
Fill the N and e values into the formula n N. Feb 26 2010 The formula does not cover finite population. If your population is smaller and known just use the sample size calculator.
Necessary Sample Size Z-score2 StdDev1-StdDev margin of error2 Here is how the math works assuming you chose a 95 confidence level 5 standard deviation and a margin of error confidence interval of - 5.
If the sample size in each group is the same. The formula for the mean employs σ2 instead of p x q as shown in Equation 7. SS1 frac Z2 p 1-p C2 S S 1 C 2Z 2p1p. Thus we should determine the confidence intervals so that all the values of the sample lie within that interval range.
