What topics/how much stats do you need to know to be a growth hacker?

I think having a clear understanding statistical concepts is extremely helpful as it gives you an edge. For example being able to know what forces are at play when doing an AB test and knowing which type of statistical test would be most appropriate is quite helpful as calculations done by software might not always be considering these things.

The other thing that statistical knowledge gives you is an appreciation for what actually constitutes correlation and how important it is to considering mitigating factors that could be skewing your results. And powerful tools like Excel take away so much of heavy lifting. If you don't know the basics of statistics you are not able to take full advantage of such softwares.