For the past week I have learned a little more about mobile Ad Monetization. I used to work in gaming as a product manager. I was releasing game features that focus a lot on pushing for IMPDAU or Ad ARPDAU. IMPDAU means impressions per daily active user. It is the count of eyeballs on an ad on a daily basis. Ad ARPDAU means average revenue per daily active user generated by ads.

There are usually two major levers that control the metrics - breath and depth. In the IMPDAU case, breath would be how many unique individuals see the ads and depth would be how many times a unique individual sees the ads. 

I don't quite understand how revenue per impression (eCPM) works before as the metric fluctuates a lot from time to time especially in the holiday season. Now I understand that it has to do with real time bidding in an Ad mediation platform. From a high level perspective, when my game requests an ad, the Ad Mediator will select the highest eCPM bidder from a list of Ad networks and settings I have chosen before, whichever gives out the highest bid wins. The tricky part here is that I can choose to limit the lowest eCPM to accept. In some cases, there will be no Ad Network bids on or above the eCPM I set causing my Ad request to not be filled. 

In summary, to maximize the revenue per impression metric, we need to find the right balance between the lowest eCPM I would accept vs. fill-rate of the ads. 

Ad network → Ad mediation → eCPM + Fill Rate → Game → Impdau