How many samples of data do you need to prove something?

From that data how would you figure out your damage range from your stat inputs so you wouldn't have to shoot 500 ruins at a training dummy each time your gear changed?

i.e if ruin 2 has a potency of 80 and I have 438 int and 300 det ruin 2 will do between X-XX damage.

That's all I have for now. I plan to expand as I answer these questions.

Edit: If there is already a resource with this information just point me to it and I'll read it. Thank you.