We regularly report our site’s Unique (monthly) Users. That data’s collected for us by omniture. If we’re ever running behind on an update, just ping me. We sell ads and so we discuss our site audience statistics publicly and with our clients and potential clients. [5,2M UU's in March - 46% of whom have annual household incomes over $100,000!] We need accurate and public traffic numbers. For better or worse, we decided to discuss UU’s and have done so pretty much since launch. We did look into being “quantified” but we unfortunately had to pass for business reasons relating to the service’s t.o.u. Sorry - for now, you’ve just got my word - and the fact that Rich would have pulled my plug by now! (ht jd!)

It’s not that I think David is lying or wrong about his numbers… But my experience is that different stat packages will ALWAYS give different results.

To give one example… While at Move, at one point, I was put in charge of organizing an A/B testing program.

Up to that point, Move (like Zillow) had been using Omniture for internal stat reporting. (By the way, you can see this for yourself by looking at the page source for the various websites).

However, I really liked the A/B testing capabilities of Google Analytics, so I helped convinced the powers-that-be to put Google Analytics on every page on realtor.com and move.com.

I won’t say which way things went, but it is fair to say that the results from Google Analytics were often substantially different than the results from Omniture…. despite the fact that both stat packages used the same technology (i.e. a bit of javascript on every page).

I say all this only to make the point that I have good reason to be extremely suspect of internal numbers… especially if you’re trying to make comparisons to other sites. 3rd Party sources may be wrong, but at least they offer a better apples-to-apples comparisons among sites.

To your other point, I was told VERY clearly while at Move NEVER to talk about internal stats for the very reason you suggest… I’m pretty sure no one wanted to open up the internal stats to investors, so we were always best off quoting 3rd party sources.

As a matter of fact, the only numbers you’ll ever see quoted by Move officials are from 3rd party sources (mostly Media Metrics).

Also interestingly, the reason I like Quantcast for Zillow is that it would offer the benefit of being 3rd party source… and, at least for me, the numbers more believable than Omniture results.