|Cost vs. Kryder rate|
What I wanted was a rough-and-ready Web page that would allow interested people to play "what if" games. What the students wanted was something academically respectable enough to get them credit. So the models accumulated lots of interesting details.
But the details weren't actually useful. The extra realism they provided was swamped by the uncertainty from the "known unknowns" of the future Kryder and interest rates. So I never got the rough-and-ready Web page. Below the fold, I bring the story up-to-date and point to a little Web site that may be useful.