I am doing a sample size calculation for a survey and am using the formula found at the bottom of this page: http://www.raosoft.com/samplesize.html
In the formula, r is 'the fraction of responses that you are interested'. What is this exactly? I thought it would be the percentage of the population I want to look at, but this is essentially the sample size I need to examine, which is the outcome answer, so that can't be right.
How do you get a value for r?