[monkeyprojects]

Originally Posted by Shane ahh bless quality score "monkey credit card" is now £5.00 a click even though ctr is 9.83% and conversion is 23% yet "monkey credit card co uk" is 0.10p a click even though ctr is 2.1% and conversion is 3.55%

I think all this actually shows is that google knows exactly how much they can get for a keyword and are using quality as an excuse to get you to pay more.

I, Cringely . The Pulpit . The Rich Get Richer | PBS shows an example of what is going on but I think it boils down to:-

On unpopular items they increase rates until the bidder stops bidding. Then slowly decrease until they start buying again.