Why this strange behaviour?

Removed all adsense code, put it on again,2 days good results now sinking

[mattg3]

Three days ago I removed all adsense code for a day from my biggest section, which used to bring the most money as the ecpm was dying a slow death.

A day later I put it back up again and for 2 days it was normal and I had more earnings than on a normal working day. Now the ecpm is dying again slowly, as far as I can see. It's as if there was a queue of ads. With taking the code of it it seems as if there was a backlog that brought normal earnings. Now again loads of empty ads and falling ecpm. :(

[leadegroot]

I beleive you are being smart priced - google's algorithms show that your visitors don't actualy make any money for the advertisers, so they reduce the cost of a click on your site, thus reducing the cost to the advertiser.
When you removed Adsense for a while the slate is wiped clean and you have a delay before smartpricing kicks in again - apparently it is about a week before it takes effect.
One solution is to switch regularly between another product and adsense.

[Eazygoin]

How does Google know if the advertiser is making money from their adverts?

Not everyone has Analytics, to provide Google with info.

Not everyone converts the same day as clicking an ad.

Not everyone is looking for a sale, that advertises.

I understood that AdWords advertisers were rewarded for the number of clicks, by getting better positioning for less money, but never heard of the price going down due to poor sales.

[leadegroot]

I only know through hearsay, but apparently adwords includes an option conversion tracking.
I agree that most advertisers propbably don't use it, so I can't guess how Google makes a generic decision of poor conversion, but the word is that they do.

[mattg3]

I have analytics, well I had, but put it on and off again twice now as the urchin server constantly slows down the page loading times, rendering the whole thing useless.

If they took the few data they have which is on slowed down server cause of themselves .. .. .. .. .. ...

[old_expat]

If you have a number of sites on the same account, do you need to remove adsense from all sites in order to "reset" smart pricing?