2  Other forces emphasized in the literature include changes in fiscal policy, the demand and supply of safe assets and the relative price of investment. Among many others, see L. Rachel and L. H. Summers, “On Secular Stagnation in the Industrialized World,” Brookings Papers on Economic Activity 50, no.
1 (2019): 1–76; and L. Rachel and T. D. Smith, “Are Low Interest Rates Here to Stay?” International Journal of Central Banking 13, no. 3 (2017): 1–42. In theoretical models, the real neutral rate is also commonly linked with trend growth, though empirical support for this link is mixed.