Forum Moderators: martinibuster
* Existing Adword advertiser meeting budget for the month and dropping out until next month.
* Existing Adword advertiser adjusting their CPC (up or down).
* Existing Adword advertiser dropping “content” sites from their campaigns.
* Appropriate targeted ad inventory become depleted triggering more PSAs.
* New advertiser joins Adword program.
* Your users profile and demographics change.
* Your website topic is of seasonal interest.
* You add or delete content.
* You change the Adsense ad format, color, etc.
* Your page views increase or decrease due to good/bad promotion, PR, linking, search engine position, etc.
* Google changes the programs payout formula.
* Google changes the targeting algorithm.
* Ad apathy sets in with your site users.
I’m sure there are other reasons. Feel free to add to the list.
They described how in just a few days the high bid might go from say X to 4X or so, just so a person could command that keyword. Evidently after some advertisers have blown through their available money the bidding returns to a more normal level. Makes sense to me.