The article examines how difficult it is to estimate the equilibrium real interest rate in real time using different models and 22 years of U.S. data. The researchers found that there is a lot of uncertainty in the models, a filtering problem, and imprecision due to data uncertainty. They also discovered that the connection between trend growth and the equilibrium real rate is weak. Overall, it is challenging to use statistical estimates of the equilibrium real rate reliably in practical policy applications.