Paid Inclusion - Predicting Performance

[James Colborn]

Predicting PFI traffic is one of the hardest variables to do based upon the 'unknown' quantity of search term and then resulting listing. PFP is much easier and there are a host of tools available for determining the performance of a campaign but as inclusion has that element of unknown my question is as follows.

What rationale do you use to determine if a PFI feed (i.e. Overture Site Match xChange) will be viable or not?

JC.