Following up this comment, anyone can run this Python script to confirm the finding that if we have TFP whose logarithm follows a Brownian motion with drift with ~ 0.7%/year mean growth and ~ 1.1%/year annual volatility for 133 years, even though the correct model is exponential growth a piecewise linear model with two pieces consistently gets lower log-L2 loss when we fit it to the data.
Following up this comment, anyone can run this Python script to confirm the finding that if we have TFP whose logarithm follows a Brownian motion with drift with ~ 0.7%/year mean growth and ~ 1.1%/year annual volatility for 133 years, even though the correct model is exponential growth a piecewise linear model with two pieces consistently gets lower log-L2 loss when we fit it to the data.