I'm working on a simple calculator on a site where given a number of sample size for an ad, click-thru rate, and confidence level, I want to estimate the number of impressions to serve. Some of the ads could be an embedded survey, as I found here http://www.printandimage.com I know, I can simply take the number of sample size a user enter, the click-thru rate a user enter, and divided them (i.e. 384 /.1% = 384,000). However, where does the confidence level and/or perhaps the survey completion rate (number of completes / number of clicks on the survey ad) fit into the formula to estimate the number of impressions?