Empirical study of a lot of cases of the tragedy of the commons and an analysis where people found a way to successfully deal with the issue versus cases where they didn't.
The fact that she actually did study analysed >100 different real world episodes of tragedy was the work that earned her the "nobel prize".
Out of curiosity, why the quotes around "nobel prize"?
This is prompted by Scott's excellent article, Meditations on Moloch.
I might caricature (grossly unfairly) his post like this: