Multiple units and CPC

On my most profitable pages I have a 468x90 unit near the top, closely followed by a 300x250 unit. This is both visual and in the html code.

I've just been checking the stats over the last 3 months and the CTR of the 300x250 unit is over 10x that of the 468 unit, whilst the average CPC of the 468 unit is ~50% higher than that of the 300x250 one.

What I am wondering is whether the higher CPC is caused by the 468 unit being loaded and displayed first or because of its size (I often see image ads in that position).

I'm going to run a few tests and experiments on this to see if I can increase the CPC of the larger unit, if I can get the CPC up to that of the other unit it would equate to an extra $100 a day in cold hard cash.

Has anybody else seen this sort of difference and been able to improve their overall revenue by making the unit with the highest CTR appear first (at least in the code).

 

I assume you know this, but the highest paying ads are those that appear first in the code. And the first ad in the ad unit pays the most. Advertisers pay more to be first.

 

I would try putting another ad other then adsense up top and then the 300x250 unit would become the first adsense ad on the page which should mean higher paid ads move down to that ad. CPC should be similar depending what other ad you put up top... ie... auctionads, azoogle, ask related search or something else.

If my little theory works then the more clicks you get on the 300 x 250 unit should be higher paid and you shouldnt loose out on the income up on the top banner spot depending on how the other networks perform up there.

 

The highest paying Ad is the first ad in your HTML code. Try shuffling them and see the results.

By the way this reminds of something i wanted to ask, if a link unit appears first in the code will it get the highest paying ads?

 

I do remember reading about this before but have never seen any hard evidence until now.

I've done the shuffle using CSS (here), so the 468x60 shows first but is second in the code whilst the larger rectangle appears second but is first in the html.

After ~500 or so clicks I'm still seeing the same CTR (as you'd expect) on both untis but the CPC has remained pretty static. So the CPC of the now second unit (468x60) is 50% higher than the first.

I will keep running the test and report my findings in a week or so.