Yes. You take all the clicks that are made in a day. Then you divide that by the amount of money Yahoo decides to pay for those clicks. And you'll have your average.
I've seen publishers earn anywhere from .15 cents to $15.00 As shez says, it greatly depends on many different factors.
What about page impressions? Do they pay any good at all? I mean Google does ok, but is Yahoo more stable or better perks?