Forum Moderators: DixonJones
1. Is it possible this is a simple case of this site using a different metric to you? Perhaps they mean that your referrals generated 5000 page impressions on their site rather then delivering 5000 unique users?
2. It is possible that a very high % of the visits to the page on your site that contains the link to this partner site are cached by proxies. This would have the effect of a large amount of your site traffic not showing up in your logs.
You could try putting a temporary page tag on the page on your site that contains the link to this partner. You could configure the tag to ensure that it busts cache etc (and maybe even set a cookie on it to keep a track of unique users over time).
This would allow you to measure more accurately the number of visits to that page so you could guage whether the partner's numbers are possible.
Hope this helps.