Binary success rates are essentially proportions: the proportion of users who completed a given task successfully. For example, if 5 of the 10 participants completed a task, the success rate is 5/10 = 0.5. The appropriate way to calculate a confidence interval for a proportion like this is to use a binomial confidence interval.
DAWSON REPORT - mention
Share this highlighthttp://www.safaribooksonline.com/a/measuring-the-user/35780/