US fourth quarter GDP data is revised today. This does not give us a slightly less ill-informed picture of economic activity at the end of last year, but it is still likely to miss quite a lot that is going on in the economy. Economies are changing faster than statisticians, and things like home working and self-employment are challenges—to say nothing of recording the economic value of the latest TikTok meme. Early GDP numbers are inclined to underreport activity, although today’s data is unlikely to correct all of that underreporting.