RMBS analytics modeling of collateral performance is evolving from a base of simplistic actuarial rating agency methodology. The current market standard for pricing is based upon roll rate methodology.  Recent Improvements in loan database quality and accessibility have allowed for the development of robust loan level methodology driven by Home Price Index (HPI) forecasts.  NIR loan level modeling is supplemented with roll rate methodology where loan data is unavailable. The two methodologies are profiled as follows: