Models like the one described in TFA bother me. It's easy enough to write down an equation, estimate some of its parameters, and tell a story about it. The har

Models like the one described in TFA bother me. It's easy enough to write down an equation, estimate some of its parameters, and tell a story about it. The hard part is making a convincing case that the model actually resembles reality: that link is the missing piece that rarely appears in modelling exercises like this one. Until you can make a convincing connection between reality and your model, all you're doing is solving equations and telling stories.