I think he may refer to the Data Development Analysis in operational research.
But in my opinion this method is seldom used in finance.
I am not familiar with it, just give some simple suggestions.
for the two dimensional case, you can draw the frontier graph to compare the efficiency of different solutions.
for higher dimensional cases, you need programming. If it is not complicated, MS excel solver can handle.
Here is a link of a document gives an example.
http://people.brunel.ac.uk/~mastjjb/jeb/or/dea.html
best,