Originally Posted by movieguy

I had this experience. It's been a couple of years so I'm hazy on the topic unless I look it up, but I recall it had to do with how google attributes the traffic.
You have to be more specific when you say the traffic is 50% less. Do you mean hits, users, sessions? It's important in GA and traffic force.

For example, google may count a hit as a pageload, but another stats program counts all http requests as a "hit".

Maybe if a user clicks a banner to go to your site, goes back, and goes forward again, that is counted as 2 users in TF, but a single user in GA.

The point is, what others said about budgeting your spend for revenue generated is correct, and there is a reason the traffic differs greatly from GA.

Also check to see if you hit your GA limits, because it starts discarding some events.