I'm not sure if I've come to the right place to ask this question, but I'm gathering some information for a research project. We're trying to design an experiment that'll heavily involve web analytics, and I'm trying to figure out some sensible values of mean +/- standard deviation for the following visitor-level (i.e., visitor 1 spends 2 minutes on site, visitor 2 spends 1 minute --> mean 1.5 +/- 0.71...) metrics:

• time spent on site
• page views

If time allowed, we would put up the sites and gather the information ourselves, but we have a grant deadline coming up. I realize that even though these the distributions of these quantities are probably going to be heavily skewed towards zero, we'll need some reasonable figures or estimates of these figures in order to do sample size calculations, etc.

Anyway, I'm not sure where else I'd turn, and I certainly have had a difficult time finding these values in the prior literature. If someone could direct me to a paper with the right information, or if you have these figures on hand (perhaps taken directly from your logs!) -- that would be amazing, and I'd love to hear from you. Thanks in advance, and even though I'm not allowed to reveal too much, rest assured that this info'll be applied towards a good cause :)