Saturday, February 17, 2018

So much for the notion that "trend real growth" is stable.

I went to MeasuringWorth and got annual data for U.S. Real GDP, 1800-2016. Added a Hodrick-Prescott trend line with a smoothing factor of 10,000. Changed the vertical axis to a log scale. It looks like this:

Graph #1: RGDP and Trend  (Vertical Scale is "Millions of 2009 Dollars")
I think I see arches in that thing. Actually, I'm not sure what I see. For a closer look I figured growth rates for 20-year periods, from 1820 to 2016. Looks like this:

Graph #2: 20-Year Trend RGDP Growth (1820 is 140% more than 1800, etc.)
Yup, arches. So much for the notion that "trend real growth" is stable.

Part 1 of 4

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