I left my MMT manuscript to rest. I think I will do another pass of reading it within the next week or so, and if I am happy, send off to my editor. It is easier to spot problems in text that you have written after not looking at it after awhile, as otherwise, you tend to read what you meant to write (and not what you actually read).
In the meantime, I have been doing research on mainstream macro, aimed at filling in some chapters in Recessions: Volume II. (Other parts of the book had been written, but the discussion of mainstream macro has been deferred.)
I wanted to write up the r* estimation algorithms, with an eye on giving a qualitative explanation as to what the algorithms are doing. However, I have been somewhat surprised by the behaviour. It is finally dawning on me that the Kalman filter algorithm has not been behaving in the manner that I expected.
The Kalman Filter is an ancient bit of control theory. It was no longer being used in the industrial applications I was concerned with, so I never paid much attention to it. From what I have seen of the control literature, there have long been concerns with its robustness. Unfortunately, it looks like I am going down the rabbit hole. Given its importance in empirical mainstream work, this is not insignificant.
Since that research is getting messier than I expected, I might be quiet on the writing front for awhile (unless I see something about fiscal policy that I want to rant about).
(c) Brian Romanchuk 2020