Based on work by English statistician David Cox (1924- ), non-nested hypothesis refers to economic models or hypotheses which cannot be obtained from another model by the use of ‘appropriate parametric restrictions or as a limit of a suitable approximation’.
Also see: economic methodology
Source:
D R Cox, ‘Tests of Separate Families of Hypotheses’, Proceedings of the Fourth Berkeley Symposium on Mathematical Statistics and Probability (Berkeley, 1961)
I like this website so much, saved to bookmarks.