Two different domains as one user session in Google Analytics

Question

I have two websites that are run as the same service. Each domain offers articles from a different market. At the top of each page the two domains are shown as menu options. If a user clicks one they can switch to the other domain.

See here: http://www.cgtag.com

Each domain has a different Google Analytics account, and when a user switches domains Google is counting this as a new session. It's listing the other domain as the "referral" for that new session. When the user switches back to the first domain Google is counting this as a returning visitor.

This is messing up my reports. Showing returning visitors values that are higher than reality. It's also increasing hits on landing pages when the user switches, and listing the other domain as a referral site.

I've found tips on how to list two domains as one website, but that results in merging the data. I want to keep the two domains separate so that I can track each ones performance, but I don't want to count domain changes as new sessions.

Maybe something like treating the two domains as subdomains.

Answer 1

This has actually been answered a couple of times on Stack Overflow.

https://stackoverflow.com/questions/4759312/session-share-across-multiple-domains-on-same-server

https://stackoverflow.com/questions/6679007/share-session-between-two-websites

Basically, it's a bad idea unless you use something like OpenID. But if you read these, you'll understand why.