Answer to Question #246088 in Statistics and Probability for Anuj

Question

Suppose you wanted to determine the perception of students in the University of Santo Tomas regarding the visit of Pope Francis in the Philippines last January 15-19, 2015. If UST has a population of 9, 250

students, using random sampling method, how many samples will be taken from this university using the formula set at .05 degree of error?

Answer 1

Accordingly, the Necessary Sample Size is calculated as follows:

Necessary Sample Size = (Z-score)² * StdDev*(1-StdDev) / (margin of error)²

For example, given a 95% confidence level, 0.5 standard deviation, and a margin of error (confidence interval) of +/- 5%. Necessary Sample Size =((1.96)² x 0.5(0.5)) / (0.05)²

=(3.8416 x 0.25) / .0025

=0.9604 / 0.0025

=384.16

So in order to get 95% confidence level, with confidence interval of +/- 5%, and standard deviation of 0.5, I have to survey 385 samples.