It has been interesting to me how much excited commentary has been elicited by my posts on output gaps. [0],
[1], [2], [3] I had thought the subject fairly uncontroversial, especially my reliance upon the CBO measure, which is calculated in a conventional manner, and is an object well-understood in mainstream macroeconomics (take your pick — from Hall and Papell to Mankiw). However, it’s clear that there is no such agreement in the blogosphere (which can be taken as an indicator of how dispersed beliefs are in that world). In any case, the reaction tells me that one’s belief in what determines potential GDP defines in large part how one thinks about the workings of the economy, and so I thought it useful to discuss alternative measures coming out of current academic work.

Recap

As I’ve discussed earlier (see this post), in some incarnations actual output is

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