A more judicious calculation, based on Table 4 of PSW, would be to say that, for example, 10 percent of loans in the historical data were misrepresented as compared with 15 percent in the crisis years, meaning that actual defaults would come in (0.85 x 1 + .15 x 1.6) / (0.9 x 1+.1 x 1.6) = 1.03 times higher than forecast defaults.

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