Lets say I have a banner manager. How would I track how long the user spent on the target website and the clickthrough of it?

Peace,

You cant tell how long they spent there I dont think. You could make them spend a certain amount of time there before credit counts though.

To measure CTR for ads, we've always directed the click to a "counter" page for that particular ad, which increments a db counter, then redirects to the desired page. That way the number of visits to the counter page pretty much reflects the number of clicks on the banner.

Determining the time spent is tougher, and we've never gone to the trouble of setting up anything. Looking at logfiles using IPs isn't very accurate, and besides, you don't know how long they spent on the last page they visited before leaving.

The most accurate method I've seen is to place a tiny i-frame at the bottom of each page, then auto-refresh the content of that i-frame every 10 seconds or so. Each time the content refreshes, it reads a cookie ID for that visitor and writes the time and ID into a db for analysis. Setting this up required more work for us than the knowledge was worth however.

Have your banner script set a session variable with a timestamp.

On the click detect script, check the timestamp against the current time and you'll know how long the person was on the last page.

Since the php file that outputs the banner will set the initial timestamp, it will only be valid if the banner is displayed. Then, its just a matter of simple math. Take current time, minus the banner time = time spent on banner page.