An IV Hazard Model of Loan Default with an Application to Subprime Mortgage Cohorts

From Christopher Palmer

This paper develops a control-function methodology accounting for endogenous or mismeasured regressors in hazard models. I first provide sufficient identifying assumptions and regularity conditions for the estimator to be consistent and asymptotically normal. Applying the estimator to the subprime mortgage crisis, I quantify what caused the foreclosure rate to triple across the 2003-2007 subprime cohorts. To identify the elasticity of default with respect to housing prices, I use various home-price instruments including historical variation in home-price cyclicality. Loose credit played a significant role in the crisis, but much of the increase in defaults across cohorts was caused by home-price declines unrelated to lending standards, with a 10% decline in home prices increasing subprime mortgage default rates by 50%.