6 These are extensions of the asymptotic single factor model (ASRF) framework of Vasicek (1987) and Gordy (2003), models in the Merton (1973) structural model framework, which have become the basis for the Basel II Advanced IRB capital framework. The extensions cited herein allow for recovery, in addition to default rates, to vary systematically; in the ASRF framework, LGD is exogenous and fixed. 7 Also see Friedman and Sandow (2002), which forms the basis of the S&P LossStats™ model, which produces predictive conditional distributions of LGD by the "maximum expected utility" method. The vendor model allows users to model the LGD at default or at resolution, in contrast to the counterpart Moody's LossCalc™, which is a regression based model built expressly to forecast LGD at the time of default.