The visitor stats Serendipity provides have stopped showing up for us (www.theagitator.net.) Is this a host issue, or has something on the Serendipity side?

Yeah, our AWStats reports 672 unique visitors, while Serendipity reports 579. Not a huge difference, but enough of a gap to raise an eyebrow.

That makes sense.

However, as I have a client to answer to, what would you estimate is a safe percentage to identify as unique users? Do you think I can say 80% of our reported number of unique users truly are unique?

OK, thanks! But is it safe to assume that each unique user truly is unique?

I am trying to figure out how Unique Visitors are determined. Is it based on unique IP addresses and therefore guarentees no duplicates, right?