8 Rachel and Smith (2015) provide a comprehensive exposition of the multiple hypotheses for the decline in the global long-run real interest rate through shifts in the saving and investment schedules, generally treating the changes as enduring.
They evaluate the estimated 450 basis point fall in the long-run real rate of interest since the 1980s with 100 basis points due to lower trend growth, 140 basis points through reduced investment demand and 160 basis points through shifts towards higher saving.