Graph #1: RGDP Fitted to the Trend Lines

Graph #2: Stages of the slowdown in real growth

It´s more or less recognized that US RGDP is trend stationary (maybe that´s changed now!), with real growth averaging about 3.3% from the early 50s to 2007

Graph #2 from mine of 28 November , renumbered:The blue line shows Real GDP. The red line is an exponential trend fitted to the RGDP data for the period 1947-1979. The green line is an exponential trend fitted to the 1980-2007 period. You can see that RGDP growth appears to have slowed around 1980, so that the green trend line falls away from the red trend line.You can see RGDP growth slow again around 2008, as the blue line falls away from the green trend line. That little blue tail over on the right seems an awful lot like the start of a third trend, lower yet than the one that dies out in 2007.I took another look at the numbers, quarterlies this time. I made close-up graphs of the trend transition periods and selected "best case" dates for the trend start- and end-points.As in the earlier post I let Excel generate exponential trend lines and formulas for the three periods. I gathered up the numbers needed to duplicate the trend lines and put them into a table along with compound annual growth rate (CAGR) values for the three periods:And I plotted the RGDP numbers along with the three trend lines, extending the latter out to the fourth quarter of 2020:By the fourth quarter of 2007 when real GDP reached 13.3 trillion, blue trend GDP was 17 trillion, more than 25% greater.By the third quarter of 2012, with the most recent real GDP number at 13.6 trillion, the yellow (1982-2007) trend shows 15.8 trillion, and the blue trend shows 20.3 trillion real GDP. For every dollar of income you earn today, the blue trend would have got you a dollar and a half.By the fourth quarter 2020, the present trend suggests 16.25 trillion RGDP. The 1982-2007 trend would have brought us to 20.5 trillion. And the 1947-1980 trend shows 27.6 trillion real GDP.So the next time somebody shows you a graph of RGDP with a constant-rate-of-growth trend line through it like this one,and when they tell you well, do not hesitate to respondPreview or download the SIMULA 7 Q&A.XLS file containing these graphs. (Q&A stands for Quarterly and Annual.)