Let's say I have 30 of those pictures
https://i.stack.imgur.com/jzxkv.jpg
I have the numbers (amounts of dots on both sides, e.g. 17 and 19) at hand, alternatively I could also do something with the distances "red dots <-> black straight line".
I would like to quantify, that on "average", there are equal amounts of red dots on both sides of the black straight line, or in other words, the big green dot has "no tendency to be sometimes at the outer rim of the red dot cloud".