I mean, what if there's a sqrt or something like that in the model. Imaginary numbers are fun to pay off, but no fun to receive :) Also: perhaps the model was

I mean, what if there's a sqrt or something like that in the model. Imaginary numbers are fun to pay off, but no fun to receive :) Also: perhaps the model was built up using empirical data and they just never really had a chance to update the model when home prices were going down... I don't find it all that weird for them to produce data-driven forecasts ;)