I have a site that receives 200+ hits a day on google analytics, I also put an iframe on this site, its a small sitewide iframe that points to another site with google analytical data also being captured. The main site should have the sam hits as the other site claims as referral hits form this site but actually it only shows half the hits? What is going on here? Its the Same tracking software, how can one site say one this and the ather pne be different using the same software? Makes no sense to me! I like the idea of analytics and the fact that its free but that just makes me wonder weather its all just a load of crap useless information? Anyone else experienced this, and not with other tracking tools just internally with google. We all know that statcounter and others all show conflicting data. At least when I do the same thing in statcounter the reffering traffic is the same as the site hits itself.
It's possible that some of your visitors are loading your tracking code and pinging Google but leaving your site before they get a chance to load the other site's tracking code and ping Google again. Try the same experiment back the other way (iFrame on the other site pointing to the main one) and see if your results differ.