The downward revisions to r* over time have been informed, in part, by the general fall in interest rates and by econometric evidence that suggests that this fall is of a permanent rather than a cyclical nature. See, among many contributors, Hamilton and others (2016), Johannsen and Mertens (2018), Laubach and Williams (2016), Del Negro and others (2017), and López-Salido and others (2020).
For discussions of the various factors that might have contributed to this fall, see Fischer (2016) and Rachel and Smith (2017). 5 For evidence on the global nature of the decline in r*, see King and Low (2014); Holston, Laubach, and Williams (2017); Wynne and Zhang (2018); and Del Negro and others (2019).