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Yield Curve and Predicted GDP Growth, August 2018

Covering July 21- August 24, 2018

  August July June
3-month Treasury bill rate (percent) 2.08 2.00 1.94
10-year Treasury bond rate (percent) 2.83 2.86 2.91
Yield curve slope (basis points) 75 86 97
Prediction for GDP growth (percent) 1.6 1.6 1.5
Probability of recession in 1 year (percent) 18.8 16.9 15.2

Overview of the Latest Yield Curve Figures

The dog days of August continued the yield curve’s trend of the last several months, with it twisting still flatter, as short rates moved up and long rates moved down. The 3-month (constant maturity) Treasury bill rate rose to 2.08 percent (for the week ending August 24), up from July’s 2.00 percent and from June’s 1.94. The 10-year rate (also constant maturity) dropped to 2.83 percent, just down from July’s 2.86 percent, itself down from June’s 2.91 percent. The twist dropped the slope to 75 basis points, down 11 basis points from July’s 86 basis points, which was 11 basis points below June’s 97 basis points. 

Despite a flatter yield curve, expectations of growth stayed essentially unchanged, perhaps buoyed by the strong showing of GDP in the second quarter. Using past values of the spread and GDP growth suggests that real GDP will grow at about a 1.6 percent rate over the next year, level with July’s estimate and one-tenth of a percent above the June number. Although the time horizons do not match exactly, the forecast, like other forecasts, does show moderate growth.

Yield-Curve-Predicted GDP Growth

Despite no change in predicted growth, the flatter yield curve led to an increase in the estimated probability of recession. Using the yield curve to predict whether or not the economy will be in recession in the future, we estimate the expected chance of the economy being in a recession next August at 18.8 percent, up from the July number of 16.9 percent, and up from June’s 15.2 percent as well. So the yield curve is still optimistic about the recovery continuing, even if it is somewhat pessimistic with regard to the pace of growth over the next year. 

Probability of Recession Calculated from the Yield Curve

The Yield Curve as a Predictor of Economic Growth

The slope of the yield curve—the difference between the yields on short- and long-term maturity bonds—has achieved some notoriety as a simple forecaster of economic growth. The rule of thumb is that an inverted yield curve (short rates above long rates) indicates a recession in about a year, and yield curve inversions have preceded each of the last seven recessions (as defined by the NBER). One of the recessions predicted by the yield curve was the most recent one. The yield curve inverted in August 2006, a bit more than a year before the current recession started in December 2007. There have been two notable false positives: an inversion in late 1966 and a very flat curve in late 1998.

More generally, a flat curve indicates weak growth and, conversely, a steep curve indicates strong growth. One measure of slope, the spread between ten-year Treasury bonds and three-month Treasury bills, bears out this relation, particularly when real GDP growth is lagged a year to line up growth with the spread that predicts it.

Yield Curve Spread and Real GDP Growth
Yield Spread vs. Lagged Real GDP Growth

Predicting GDP Growth

We use past values of the yield spread and GDP growth to project what real GDP will be in the future. We typically calculate and post the prediction for real GDP growth one year forward.

Predicting the Probability of Recession

While we can use the yield curve to predict whether future GDP growth will be above or below average, it does not do so well in predicting an actual number, especially in the case of recessions. Alternatively, we can employ features of the yield curve to predict whether or not the economy will be in a recession at a given point in the future. Typically, we calculate and post the probability of recession one year forward.

Of course, it might not be advisable to take these numbers quite so literally, for two reasons. First, this probability is itself subject to error, as is the case with all statistical estimates. Second, other researchers have postulated that the underlying determinants of the yield spread today are materially different from the determinants that generated yield spreads during prior decades. (For a recent example, see “Recessions Probabilities.”) Differences could arise from changes in international capital flows and inflation expectations, for example. The bottom line is that yield curves contain important information for business cycle analysis, but, like other indicators, should be interpreted with caution. For more detail on these and other issues related to using the yield curve to predict recessions, see the CommentaryDoes the Yield Curve Signal Recession?” Our friends at the Federal Reserve Bank of New York also maintain a website with much useful information on the topic, including their own estimate of recession probabilities.

Explanation of Revisions
Corrected Data

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