29  For estimation purposes, 𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑆𝑡𝑡 is approximated using the unemployment rate  less the Congressional Budget Office’s (CBO) historical series for the long-run natural  rate.
From 2007 to the present, 𝜋𝜋𝑡𝑡𝑒𝑒 is approximated using the median forecasts of long29  Although the data used in the decomposition analysis have been revised and extended, the specification of the model and the estimation period are the same as that discussed in a speech I gave two years ago (Yellen, 2015).