I keep forgetting to output the real GDP growth rate (nominal GDP growth rate minus inflation). Using the results from the previous post, here is the RGDP growth rate (LOESS smoothed is darker blue):
Here is the smoothed RGDP growth rate (blue, from the previous graph) compared to data from the FRED database (green):
This isn't saying too much more than the previous results -- we take NGDP growth and subtract the inflation rate which means if you get inflation almost right (as we did), you get RGDP growth almost right. The problem areas are in the same place (near the Volcker disinflation and the Bernanke quantitative easing).
It is not as obvious with the smoothed model results how well this actually nails RGDP growth (except during the Bernanke quantitative easing); here is the non-smoothed version: