I spent the summer of 2011 helping mortgage borrowers (i) correct bank documentation regarding their loans and (ii) extract permanent mortgage modifications from banks. One of things I did was check the bank modifications for compliance with the government’s mortgage modification program, HAMP, and with the HAMP waterfall including the HAMP Principal Reduction Alternative. At that time I put together HAMP spreadsheets, and typically when I read articles about HAMP I go back to my spreadsheets to refresh my memory of the details of HAMP.
So when I learned about a paper that finds that HAMP “placed an inefficient emphasis on reducing borrowers’ total mortgage debt” and should have focused more on reducing borrowers payments in the short-run — which goes contrary to everything I know about HAMP, I decided to read the paper.
Now I am an economist, so even though my focus is not quantitative data analysis, when I bother to put the time into reading an econometric study it’s not difficult to see problems with the research design. On the other hand, I usually avoid being too critical, on the principle that econometrics is a little outside the area of my expertise. In this case, however, I know that very few people have enough knowledge of HAMP to actually evaluate the paper — and that many of those who do are interested parties.
The paper Peter Ganong and Pascal Noel’s Liquidity vs. wealth in household debt obligations: Evidence from housing policy in the Great Recession. This paper has been published as a working paper by the Washington Center for Equitable Growth and NBER, both of which provided funding for the research. Both the Wall Street Journal and Forbes have published articles on this paper. So as one of the few people who is capable offering a robust critique of the paper, I am going to do a series of posts explaining why the main conclusion of this paper is fatally flawed and why the paper reads to me as financial industry propaganda.
Note that I am not making any claims about the authors’ motivation in writing this paper. I see some evidence in the paper to support the view that the authors were manipulated by some of the people providing them with the data and explaining it to them. Overall, I think this paper should however serve as a cautionary tale for all those who are dependent on interested parties for their data.
Here is the overview of the blogposts I will post discussing this paper:
HAMP and principal reduction post 1: The ideology of financialization
HAMP and principal reduction post 2: What’s the problem with financialization?
HAMP and principal reduction post 3: A regression discontinuity error
The principal result in the paper is invalid, because the authors did not have a good understanding of HAMP and of HAMP PRA, and therefore did not understand how the variable they use to distinguish treatment from control groups converges to their threshold precisely when principal reduction converges to zero. The structure of this variable invalidates the regression discontinuity test that the authors perform.