New ads with same size and placement resulting in lower RPM

Can simply creating new ads w/o changing size or placement affect page RPM?

[rocketsites]

A few days ago I renamed a few of my best performing ad units in order to better identify them. I also created 4 additional ad units of the same size in order to better track Revenue, RPM, etc across our three most highly trafficked page templates. These new ad units were placed in the exact same spots as the old ones, so ad size and placement are unchanged. Only the ad units themselves are new.

Yesterday after the change was made, we had a huge drop in page RPM but ad impressions and page views remained unchanged. This indicates to me that simply creating a new ad unit may cause the ads themselves to target users less effectively and thus result in less clicks. has this happened to anyone else? Does it take time for Adsense to "learn" which ads to serve even though it should theoretically already know what ads to serve users based on the domain and other ads?

[matbennett]

If nothing else has changed and the RPM is only lower on the new units I would check that you were not picking up placement targeted bids on the old units. If you have a few regular campaigns targeting you that can make a difference. I'd also check that you are definitely comparing like for like. If you created the units in order to improve reporting granularity that suggests that you don't have like for like 'before' data. Ideally you'd now split test the two units, but if there are now CPM drops on other units you could compare a before and after combined CPM from the old + new units.

[NickMNS]

@rocketsites
It is also possible and even likely that the drop in RPM has nothing to do with the changes you made and are simply the result of market price fluctuations. It is the beginning of a new month and new quarter.

You will need to give it time to be able to get a sufficient amount of data to eliminate the impact of any such daily fluctuations (+ or -). And by waiting longer to collect more data, you may lose the impact of what you described. So will likely never know, and you'll be stuck waiting it out regardless.

If you are really interested in seeing if what you describe can have an impact, you could trying setting up an A-B test with "experiments" in Adsense. Like that one would maintain the current state, and have a new state in the same market conditions thus controlling for these conditions.