Ragot said new dev teams can even just focus on one metric: “If there is one KPI, according to my experience, that tells you everything, it is “Retention at Day X”. D1 retention is how many people come back to your app in the same day after they install it. I am always looking at D1, D3, D7, D14 and D30. If you put all of your effort into measuring this, you have good analytics that is a mix of retention and acquisition.”