Multiple Coversion scripts on one page?

[ebiz97381]

Does anyone know how Conversion scripts determine whether or not to count a sale or not? I have Google and Yahoo conversion counters on my site. How does the Yahoo script know that the sale came from Google or visa versa?

Thanks

[edited by: Woz at 5:32 am (utc) on Sep. 8, 2004]
[edit reason] No sigs or URLs please, see TOS#13. [/edit]

[jatar_k]

Welcome to WebmasterWorld ebiz97381,

in scripts that I use for tracking I grab the initial referer and then save it to a session which in turn carries it all the way through to a purchase/signup page. I can then use that original referer to find out how they got to the site and then attribute that particular sale to that referer.

I would imagine that those tracking scripts do something similar with cookies or sessions.