I know it seems idiotic, but I have this problem and my knowledge is not enough to solve it.
I am coding a simple DEA model in GAMS for 55 DMUs (Decision Making Units) with 8 input and 2 output in order to compute the score.
But the problem is, all score are 1. When I put some restriction on weights, the in-feasibility appears.
I really appreciate any suggestion to solve my problem.
Thank you in advance.
It's theoretically possible for any number of DMUs to all be "efficient", but it certainly seems unlikely.
The first thing to do would be to test the correctness of the model. I'd suggest creating a spreadsheet with the 55x10 table of inputs and outputs, plus 10 cells for the weights assigned to the inputs and outputs and 55 computed efficiencies using those weights. Take a random sample of DMUs (you probably won't want to do this all 55 times), run the DEA model with that DMU as target, plug the resulting weights into the spreadsheet and confirm that the target DMU has efficiency 1 and all others have efficiency <= 1.
answered 23 Jan '13, 18:43
Paul Rubin ♦
I've looked at the GAMS model (which seems correct to me, although I don't use GAMS). I also replicated the model in AMPL with the shared data and observed that every DMU scored an efficiency rating of 1.
answered 26 Jan '13, 14:40
Paul Rubin ♦