does long-time used ad formats pay better?

[sallam]

I noticed this, but I may be wrong:
I've been displaying an adsense banner for a long time. Then recently I replaced it with a 200x200 box, in the same place in the page. The CTR is now almost the same as before, but the epc (earning per click) dropped dramatically, less than half what it used to be.
Does ads give better revenues when they age? and why new formats in the same place with same ctr gives less epc?

[MThiessen]

No, I don't believe so. I juggle em around all the time looking for better combintations of colors, size etc etc. Never got dinged for it. Might be something else you did. Put the old one back and see what happens.

[RiverStoneX]

You need to do the testing for a long period of time since you could be in a low paying period of the month.
Anyway, I think you are right because google adsense uses LEARNING technologies to display the best ads. During the first days, less targetted ads (less paying also) are displayed.
What format did were you displaying before?

[Quadrille]

It depends.

On your audience
On the add content (different advertisers favour different formats)
On the bid (some formats are more in demand)

On your page design - some ads can make a page look MFA, where previously it looked tasteful. Visitors are slowly learning to distinguish cr*p sites from quality, and you need to be sure you are on the right side of that fence!