I can't do basic math, but my competence is in other things...Help?
March 14, 2013 7:54 AM Subscribe
We want to assess a list of vendors in two domains: Accessibility and Cost. We have two tools that we are using to essentially score them in each of these domains separately. The Accessibility assessment tool totals 110 points; the Cost tool totals 90 points. We want a final score for each vendor that combines the domains and is out of 100. We want the Accessibility score to "count" about 20% more than the Cost score in the final because it is more important to us. How do we do this?
posted by OmieWise to science & nature (10 answers total)
Were both domain scores out of 100 this would be easy: we would simply multiply Accessibility by 0.55 & Cost by 0.45.
Some folks are proposing that because there are already about 20% more points in the Accessibility section, we simply add both together and average. (The two sections add to 200 points.) I know from brute arithmetic that this does not work exactly in the middle of the range (although it does at each end), but I'm having trouble articulating why not. There are more points to gain or lose in the Accessibility section, but does that translate to a greater weight being placed on Accessibility?
I would like to find a solution that "weights" Acc. 20% more than Cost.
I would like to understand why the proposed average does or does not do that.
I would like the solution to be as transparent as possible so that vendors can understand the results even if they are as challenged as I am. (Assume they will be, this is not about cost or access and the vendors are not business people.)
Can you help?