3
$\begingroup$

There's probably a very simple answer to this, but I can't put my finger on it.

I have two numbers. I want one to be large, and the other to be small. I'd like to identify these with a single value.

For instance (hypothetical example follows), students should have high test scores and low absence rates. Therefore, a student with a test score of 100 and an absence rate of 0 is the ideal student.

For the purpose of this example, the absence rate is the more important number. We'd rather have a student with a test score of 50 and has an absence rate of 1 than a student with a test score of 100 and an absence rate of 2. In other words, it's most important that the small number is actually small.

So taking test score / absence rate won't work. Because in the aforementioned example, it scores both students equally. Additionally, a student with perfect attendance throws a divide-by-zero error.

Any suggestions? Is there actually a simple answer? I apologize if the question is too elementary for this site.

Thanks!

P.S. I couldn't identify an appropriate tag, so please re-tag if you can think of a better one.

EDIT: Reading through my question, I see that it could depend on how much more important the small number is than the big number. Really, I'm not concerned with the particulars. A general answer is all I need to craft a solution to my specific problem.

  • 0
    Maybe you are looking for a function like $f(x,y)=xe^{-y}$, which is linearly increasing in $x$ for fixed $y$, and exponentially decreasing in $y$ for fixed $x$.2011-05-29

1 Answers 1