Opinion on how to calculate "Returning Visitors"

[fischermx]

I'm developing a sort of website analytics solution with adsense and outgoing clicks tracking(sounds like a big thing, doesn't it, lol), well, the thing is I'm facing configuration issues.

Most of the tracking solutions, give you an option to setup how much time elapsed should be consider a user a new visit. Just like Google Analytics is 30 minutes, other allow you to setup this value to 1 hour or more, whatever. Well, my question IS NOT about this.

I'm talking about Returning Visitors. A returning visitor is someone that visited your site yesterday, or last week, or last month and returns today. It is a new visit today, but is it a new visitor overall?
How much time would you consider to be elapsed to count a visitor as a new visitor, instead of returning? a week? a month? a year?

I think most cheap/free tracking solutions are totally careless about this, and they consider a returning visitor as long as your tracking cookie stays on the visitors computer. I've seen addfreestats showing a "Returning Visitor" when the last visitor was 6 months ago, for example. I think someone that came to your site (well, depending on the type of site), but most likely, after 6 months, he/she forgot about you and just found you again.

What's your opinion on this?

[larryn]

Depends,

If an visitor who has been to your site before comes in from an external link, after xx days, they are not really returning are they, but if their first page is not a published entry point and they have it bookmarked, even a year later, aren't they really returning.

The bigger question is, what do you need to know about returning visitors, in order to take what action depending upon the information?

Larry

[fischermx]

Well, you need to know about the returning visitors data because it is a very important metric.
What actions to do upon data? Well, that's depend too much on the site. But everybody knows that for retuning visitors, the bigger the better.

Now, you have raised very valid points. Even two years later if it looks like a bookmark (or memory), then it is a returning visitor. In the other side, if it found you on the SERPS, that does not count too much. By a link on other site is yet another story.
I think I will do then what others do. As long as there's the cookie it is a returning visitor, but then, I will split the data to show how that returning visitor returned.