[rbinv]

If cookieless, how do you accurately aggregate/assign pageviews per visitor?

[yummyfajitas]

Browser fingerprinting is one possible way.

https://panopticlick.eff.org/

[edit: clarified that this is a solution, I have no knowledge as to whether that is what is done.]

[rbinv]

Do you actually know that fingerprinting is used or is just an assumption?

[ryan-c]

They seem to only be collecting screen resolution, viewport size and whether ads are showing client side (tested by trying to load a file called ads.js that inserts a div into the dom). I assume server-side they combine this with user agent string and ip address.

[amorgan]

Screen resolution & viewport size aren't being used. They were added many months ago when we first started development.

[ryan-c]

So you're just doing UA + IP? Seems like that would be plenty for your use case.