Reports collapse quickly if these three are treated as one score. Each one is allowed to move without the others.
Fill rate
Fill rate is how often a request that you sent comes back with an ad. It says nothing about the price, and nothing about whether the ad rendered.
eCPM
eCPM is the revenue for a thousand impressions, usually after you have defined which impressions count. A high eCPM on a tiny slice of traffic can sit next to a weak day overall.
No-fill
No-fill is the response that says this opportunity has nothing. A good setup does not stop there. It goes to the next configured partner, or to a refreshed request, instead of leaving the slot empty.
