{'fraction_non_alphanumeric': 0.021233569261880688, 'fraction_numerical': 0.004044489383215369, 'mean_word_length': 4.593220338983051, 'pattern_counts': {'":': 0, '<': 0, '<?xml version=': 0, '>': 0, 'https://': 0, 'lorem ipsum': 0, 'www.': 0, 'xml': 0}, 'pii_count': 0, 'substrings_counts': 0, 'word_list_counts': {'cursed_substrings.json': 0, 'profanity_word_list.json': 0, 'sexual_word_list.json': 0, 'zh_pornsignals.json': 0}}
[Pitfalls and Opportunities: What Macroeconomists Should Know about Unit Roots]: Comment

This paper is an outstanding survey of unit root econometrics. It is an enormous and confusing literature, and Campbell and Perron's 24 rules are a tremendous and very practical condensation. If you decide to run unit root tests, this is a good place to start. Rather than pick on rule 22, or survey some fields that the authors left out of this already massive paper (such as the Bayesian view or fractional unit roots), I will devote my comments to some reservations on practical usefulness. The bottom line is that, as much as I admire this paper as a survey of what econometricians know about unit roots, I am not yet convinced that this is what macroeconomists should know about unit roots. For the moment, there are two broad uses of unit root econometrics, and I think it is best to organize my thoughts about what macroeconomists need to know about unit root econometrics by how they use it.