Figure 3. Detrended Freight TSI, Detrended and Smoothed Freight TSI and Growth Cycles: January 1979–December 2016
Shaded areas indicate decelerations in the economy (growth cycles). Detrending and smoothing refer to a statistical procedure that makes it easier to observe changes in upturns and downturns of the data. Detrending removes the long term growth trend and smoothing eliminates month to month volatility.
Calculated by U.S. Department of Transportation (USDOT), Bureau of Transportation Statistics (BTS) from USDOT BTS, Transportation Services Index, available at www.bts.gov