As the Federal Housing Finance Agency considers whether to update the credit scoring models used by Fannie Mae and Freddie Mac, a new paper from Dr. Clifford Rossi explores the risks of introducing multiple credit scores to the mortgage lending system. Specifically, Rossi examines "the effects of alternative credit scoring models on credit risk, profitability and effectiveness at expanding access to credit," using three hypothetical mortgage score models and a large sample of GSE loans originated between 1999 and 2015.