The answer is that it has not passed any peer review, it is a "working paper" only available to "associates" of MIT-CEEPR: http://ceepr.mit.edu/publications/wor

The answer is that it has not passed any peer review, it is a "working paper" only available to "associates" of MIT-CEEPR: http://ceepr.mit.edu/publications/working-papers/681 http://ceepr.mit.edu/publications/working-papers/681 If you read the back-cover of any of these CEEPR working papers, it includes a disclaimer stating that they have not passed any peer review: CEEPR releases Working Papers written by researchers from MIT and other academic institutions in order to enable timely consideration and reaction to energy and environmental policy research, but does not conduct a selection process or peer review prior to posting