7. The longer-term outlook for where rates will settle is even more uncertain, and not only because the more distant future is always harder to forecast. Despite the long-standing love affair of macroeconomists with the notion of a “neutral”, “natural”, or “equilibrium” real interest rate, we don’t find r* a very helpful concept. Beyond the
econometric issues with popular models such as Holston-Laubach-Williams, the key
economic problem is that the impact of the real interest rate on GDP is economically small, statistically insignificant (at least in recent decades), and too easily disturbed by shocks to financial conditions. This means that backing out the “neutral” rate from the behavior of the economy is challenging, to say the least. What we can say is that real rates during the 2009-2020 expansion look like a
low-side outlier relative to the longer-term cross-country norm of about 1%. This makes the 5-year 5-year forward TIPS yield of about 0% look too low in a probabilistic sense, although a large increase may require actual Fed hikes that push real rates into meaningfully positive territory without large adverse economic effects—and we don’t expect that test case to occur for another 4-5 years.