https://www.nber.org/system/files/working_papers/w29079/w29079.pdf
Authors. Casey, K., Glennerster, R., Miguel, E. & Voors, M
Venue. (NBER Working Paper 29079)
How the Institute flags it
established 3 times frontier 1 time
This source carries more than one flag across the corpus. That is not an inconsistency to resolve: the same work can be established evidence for one claim and frontier evidence for another, and the flag belongs to the use rather than to the source.