Anyone know what is CPM Imps?

In the admob site reporting, there is a column with “CPM Imps”.
I notice that one of my app has averagely 200++ “CPM Imps” per day. In the last two days, the “CPM Imps” for the app rise to 600++. The revenue per day, CTR, eCPM has not changed much.
For others of my app, the “CPM Imps” is always less than 30.

Is there anyone can tell me what is the meaning of “CPM Imps” or how it is calculated from any datas.
Thanks a lot.

CPM impressions are impressions you are paid for based on factors other than clicks. Many factors affect the earnings here like geos, refresh rate or app category.

Admob generally runs CPC impressions where you are paid for clicks on the ads, whereas they now run CPM impressions too.

Is there any unnormal with the CMP Impressions that is so high for the app compared with others?

I’m not sure how Admob manages the two types sorry. I guess CPC suits some traffic types, while CPM suits another.
As far as I’m aware you have no control over which type is served…

Excuse me…but I don’t get it why admob won’t let developers have control over what type of ads they want to be served…

I know developers can have their own costumized ad format in some other ad networks…

I think it’s something to do with the AdSense backfill? I mean using AdSense is completely optional, so I guess they are letting you control the ads that are being served.

As it stands I’m only getting like 1% of my impressions serving CPMs, the rest is CPC.