When assessing ad network performance, many publishers focus on CPM. The problem with this is that CPM does not give the full picture of any performance inefficiencies. This is because naturally certain impressions are less valuable for advertisers (based on country, point in the user session, etc.) and so generate lower CPMs.
To optimise revenue you have a few options:
- Make your app attractive to a global audience
- Use a mediation platform such as MAX Mediation and add a variety of ad networks to compete to show ads to your users