Rate Of Adoption
  
New minus Old, all over Old. That's the magic formula in calculating rate of adoption problems.
Male teens in Florida, aged 13-18, have downloaded your app, GatorMeat, a new bodybuilding program. You estimate that there are a million targets in your market. Last month, only 10,000 units had been downloaded. And 3 months later, 40,000 were downloaded. Your adoption rate went from 1% of the market to 4% in only 3 months. Feel the burn.