A new research paper aims to settle the debate about whether loose underwriting or the downturn in home prices was the biggest factor in the poor performance of subprime mortgages originated before the financial crisis. There was a sharp divergence in the performance of subprime mortgages originated in 2003 and those originated in 2006 and 2007. Some have suggested that the subprime mortgages originated just before the crash defaulted at higher rates largely because underwriting standards on the loans deteriorated, while others claim the main issue was that house price declines left the borrowers with negative equity. A paper by Christopher Palmer, a professor of real estate at the University of California at Berkeley’s Haas School of Business, claims...