CPC not always what you are paying?

[zeus661]

Suppose I have an adgroup and set all keywords at $1. Why is it some keywords are charged LESS. Not that I am complaining but shouldn't they all cost $1 when clicked?

I have seen some keywords get billed at less than half of what I have the bid set for. Why does that happen?

Thanks in advance.

[FromRocky]

The actual cost per click for each kw is calculated based on its ad-ranking number, CTR and the ad-ranking number of one-below ad. All of these parameters are diffrent for each kw even you set them at the same bid.

[patient2all]

Zeus,

Taking it at its simplest form, if you were the only bidder on a keyword, surely you wouldn't want to or expect to pay $1.00. You'd pay a nickel.

patient2all