Affiliate Marketing is becoming a mature industry (or so we are told) - yet most merchants still don't understand what works when it comes to affiliate incentives.
Let's start with a basic fact of life for most affiliate programmes - 80-90% of your sales will be provided by between 2 and 15 affiliates, with the rest providing the other 10-20%.
Even within those 2-15 it is not atypical for 1 affiliate to generate 3 times as many sales as their nearest rival.
SO - given those statistics (and no one from any major merchant or agency has yet disagreed with me on them whenever I have presented them) then it should be clear that any competition where a bonus is awarded to 'the affiliate who makes the most sales this week/month/year' is not really a competit...