November 15, 2021

Model Update: Trend Inflation Models


The inclusion of the fourth quarter has resulted in an additional upward tick of the mean across models, following a steady increase in the last three quarters. The models now suggest that trend inflation is a bit above the Fed target. The average across all models (the solid black line in Figure 1 below) is estimated at 2.3 percent in 2021:Q4, 4 tenths higher than the pre-Covid.


It is not a surprise that most measures of trend inflation are revising up their estimates in reaction to high incoming data, given the size of the shock. Nevertheless, the inclusion of Q4 has triggered upward revisions even for the most persistent models (the TVP-VARs). Needless to say, the usual disclaimer about the end-of-sample uncertainty applies.

Implications    for the Fed staff

The estimated average across models can be taken as one of the three ways to estimate underlying inflation or pi* (the other two being the evidence from long-term inflation expectations, and the general equilibrium approach considering the interaction between pi* and U*). As a reminder: the level and evolution of pi* is the crucial assumption in the Fed staff framework/forecast and it is possibly the single most important variable for monetary policy. We continue to believe that the staff has set pi* to 1.8 percent, flat in history and in the forecast (the black dashed line in Figure 1). As such, the evidence from the trend models continues to signal upside risks to the medium-term Fed staff forecast.

Figures and Tables

Figure 1

Note: the chart shows the estimated trend inflation from 11 econometric models. The models are split into three groups. The first group is a collection of Phillips-curve (PC) type of trend inflation models in which a measure of long-term inflation expectations is used as a proxy of trend inflation. The second group is a collection of state-space unobserved component models in which we have modelled trend inflation either as a smooth trend or as an augmented local level. Finally, the third group of models is a collection of Time Varying Parameters Vector AutoRegressive models (TVP-VAR) with different endogenous variables. This set of models follows the FEDS Note by Rudd (2020) Underlying Inflation: Its Measurement and Significance”. The Fed staff assumption about the level of underlying inflation (set at 1.8 percent) is inferred from Laubach et al. (2014) “Long-term Inflation Expectations and Risks to the Inflation Outlook“.

Table 1

Note: the 70% confidence intervals refer to 2021:Q4. The “Average” line is calculated as a simple mean across all models.

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Trezzi consulting is a Swiss registered firm that offers independent economic and statistical consulting services. Trezzi consulting does not have access to any classified information of any central bank, including the Federal Reserve. All econometric and statistical models included in the packages are either developed in-house or they are based on publicly available documents such as papers and notes.