Max CPC's Relationship to Actual CPC and Impression Share

Relationship Between Max CPC Bid, Actual CPC and Impression Share

Hi Roy, I had a question in regard to Max CPC bid, Actual CPC and Impression share. One of our campaigns in PLA has been over-target ROI significantly for a few weeks. Impression share is at the 60% range and I would love to push that into the 80% or more. What’s odd is that our max CPC bids in some cases can be in the $2-$3 range and our average CPC’s end up being in the 30-60 cents range. I did check in on our auction insights and it looks like we greatly outrank our competition in impression share. This implies that CPC’s aren’t being driven up due to lack of competition. I feel a bit skeptical about this though. Any thoughts? I don’t understand why google wouldn’t want to sell me those extra impressions.

When the actual CPCs are coming in much below the Max CPC Bid, then a lack of competition is the first thing that comes to mind to me, as well.  While your impression share is strong, it's not so high that I expected to see $2.50 bids coming in at $0.50, though.  However, the way you're interacting with other sites in the search auctions is still the only thing that affects CPCs like that, relative to bids.

What this might uncover is an opportunity with the product data, such as the titles.  While I'm sure you're feeding in UPCs, it may be possible that Google isn't matching your products with all of the searches that they might be relevant to.  For example, if I passed in a bunch of titles that were too short, then I would see apparently reduced competition--along with a significantly reduced impression pool, relative to a feed that was more robust.

Negative keywords can also have an impact so make sure there aren't any overzealous negative keywords limiting you from quality impressions.

Bid adjustments also may play a role in the delta you are seeing between the max CPC and actual CPC.  Let's look at a typical mobile bid adjustment. If half of the clicks are mobile and mobile bids are half as much as desktop bids then the total average bid would be 3/4 what it would otherwise be and it wouldn't be reported at all.

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