A group of sites with Google Analytics

My online magazines are distributed over some subdomains

[jetteroheller]

The current situation is:

I have for each subdomain a differend tracking code.

But I would also like to know the performance of the site as whole.

I mean for example how long visits a visitor?

The same visitor could visit 5 different subdomaint

a.example.com 2 page views 60 seconds
b.example.com 3 page views 90 seconds
a.example.com 1 page view 20 seconds
d.example.com 5 page views 300 seconds

But I would like to see a combinded statistic where this 1 visitor coutns as

*.example.com 11 page views 570 seconds.

This would be very important, for example I just make a layout change.

The average visit time on
www.example.com goes down, the average number of page views goes down,
but www.example.com is the distribution page between the different subdomains.

So when somebody visits www.example.com and clicks because of interesting news to an article on a.example.com is complete different from leaving my site.

But I can not find it out.

[mark_roach]

I think you will need to use a single tracking code. There is a page in the Analytics help section detailing the steps you need to take.

Tracking Subdomains [google.com]

If you also wish to track your subdomains seperately and keep your existing tracking codes you could use Multiple Tracking codes [webmasterworld.com].