It is an equation, albeit probably flawed somewhere down the line.

N = R* • fp • ne • fl • fi • fc • L

https://en.wikipedia.org/wiki/Drake_equation

An excellent use of rough statistics to shatter long held beliefs. Even if life is incredibly rare, it most certainly exists somewhere else.

This equation was the first serious attempt to quantify the number of civilizations in our universe. As we explore Europa and others, we will get some serious data points to improve our understanding of the origin of life in the universe.