The author develops a strategy for utilizing higher moments and conditioning information efficiently, and hence improves on the variance bounds computed by Hansen and Jagannathan (1991, the HJ bound) and Gallant, Hansen, and Tauchen (1990, the GHT bound).
First, I should explain what I mean by flexibility. As most of you are surely aware, the Bank of Canada has been openly discussing the importance of promoting policies that support economic efficiency, including financial system efficiency. Efficiency refers to the allocation of scarce economic resources to the most productive uses, in a cost-effective way.