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Problem figuring out on how to create a scoring sytem

  1. Sep 24, 2011 #1

    I'm creating a scoring system but I think the whole base of it is wrong and I don't know how to fix it.

    It's simple. There are 3 criteria: A, B and C. I will evaluate people in those 3 criteria and attribute points to it.

    Criteria A need to be 30% of total
    Criteria B need to be 40% of total
    Criteria C need to be 30% of total

    So what I do is attribute points and then multiple by 30% or 40% and then sum them all.
    The problem is that those criteria do not have the same amount of points.

    Criteria A can go from 0 to 6.
    Criteria B can go from 100 to 600.
    Criteria C can go from -2 to 2.

    So when I sum them, it doesn't make any sense. For example:

    John got 5 on A, 400 on B and 1 on C.
    A: 5*0.3 = 1.5
    B: 400*0.4 = 160
    C: 1*0.3 = 0.3
    Total: 161.8

    This way doesn't seem that criteria A is having the same importance of criteria B, or at least only 10% less importance.
    How can I make that work? Because it's impossible to have same scoring system for all criteria, but somehow the final score should reflect all criteria as almost equal.
  2. jcsd
  3. Sep 24, 2011 #2
    You need to find the percentage of possible points for each stat, then multiply by the percentage of the total score. That's confusing, so I'll give an example.

    For A = 5, B = 400, C = 1:
    A is 83.333...% of its possible points. Computed by 5/6.
    B is 80% of its possible points. Computed by 400/500.
    C is 75% of its possible points. Computed by 3/4.

    The general formula for a stat named S is (S + min)/(max - min) where S is the number of points for the S stat, min is the minimum number of points, and max is the maximum.

    You can then take those values, and plug them into the formula you were using.

    83.333... * .3 + 80 * .4 + 75 * .3 = 79.4999... on a scale of 1 to 100.
    Last edited: Sep 24, 2011
  4. Sep 25, 2011 #3
    Thanks! That solved my problem.
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