I currently have 3 ad units on one site but I am thinking of cutting it down to 2. Will the clicks then pay more? In your experience what gives more revenue, much ads or only a few on the correct places? Thanks.
Theoretically, less ad units will mean higher CPCs, because Google will cut the worst performing ads, which often means the lower paying ads. But that doesn't translate to higher earnings, as your CTR should go down as well.
Going with few adds, that will increase your eCPM, which help you to generate more revenue for less clicks. But it can also down your CTR. Try it and see the results.
It has nothing to do with how many units you're running on a page. Usually, the first placed unit receive ads with higher CPC's, but I guess that there is not so much difference in placeing 3 units or only one. When under a searched keyword the cpc is high then all the others are about the same too or just a few cents lower.
my first placed unit has highest CTR and eCPM. I tried single ads unit and max ads unit, it does not make much different. Instead, I get few bucks more by putting one more ads units (the first placed unit earns few times more than it).
Hmm. My first placed ad units have very low CTR compared to the other two. I will change it know and see what happens.
Assuming you can do as follows, if you had 3 different places for ads and you want to try only 2 units, remember to test different positions moving the ads around, as it might make a more significant difference than just the number of ads.