I have some two models and I need to compare the efficiency of one to another one.
But if one model produces negative result e.g. -10 and another one positive eg 30, mathematically the ratio is 30/-10 = -3 meaning the first one is -300% effective to another one, which is mathematically correct, but incorrect otherwise.
What is the ratio in this case you think? I would say 400% because it is one piece of 10 to the zero, and then another 3 pieces up to 30.
Another question is what if one is 30 and another 0 that is 30/0. It is illegal in math to divide by zero, but how to express the efficiency in this case? Is it 30x or what is it? Hard to express again.
Mathematically it is infinity or illegal, but in reality it's not that big.