There is 2 main factors that affect your final earnings:
- The Country/Region of the Installations
- Game Retention Rate
Installs from Tier 1 countries (USA, Canada, Australia etc) can make you more money per ad impression compared to Tier 5 (Egypt, Pakistan, Barbados etc). On the other hand, competition is higher in Tier 1 countries, especially English speaking countries. Localising an app for a less popular market can lead to increased visibility and more installations.
Game retention rate is directly related to ads impressions. The more a user plays your game, the more ad impressions that are made, and this leads to more revenue. The number of installations is a good measure of the size of your user base, but it does not indicate how long they have played your game and the number of ad impressions. A good strategy to maximise your earnings is to focus on improving your retention rate by having interesting content, easy to understand prompts, and plenty of content. The longer they play the more your earn.