• Pat Grady

    Since every imp is still an auction, I’d guess they convert your CPM bid to an effective CPC bid… meaning this is convenient if you’re a CPM bid minded buyer, but underneath, again I’m assuming here, the auction action is the same, based on eCPC. So, where you have a high CTR, your per imp eCPC will therefore be lower… and vice versa. Something to think about regarding your specific goals.

  • Bryant Garvin

    Hey Pat, it is actually just the opposite. they “normalize” everything to an eCPM for each auction. As an Adwords advertiser you can actually see your ecpm as a column in Adwords.

    I actually just touched base on this a couple weeks ago – http://www.getfoundfirst.com/blog/the-google-ecpm-game-the-importance-of-ad-rank/ but yes every imp is an auction this is just one new way they can try to raise the eCPM across the board and increase revenue for them and for their publishers.

  • Pat Grady

    The “e” in eCPM stands for effective, they are converting CPC into an effective metric that some people prefer to use, so they can see data the way they prefer to see it presented, but the underlying auction is always a CPC auction.

    That said, it actually doesn’t matter if you convert CPM to eCPC and have a CPC auction (my assertion), or if you convert CPC to eCPM and have a CPM auction (your assertion) – the point is, in either direction, that they use CTR to equate the two things, head to head, in an auction.

    If you bid CPC:
    +your low CTR auctions will win less.
    +your high CTR auctions will win more.
    Your spend is focused where it is most relevant.

    If you bid CPM:
    +your high CTR auctions will win less.
    +your low CTR auctions will win more.
    Your spend is not focused on relevance, so it has a broader reach.