The Yield Curve, August 2008
Since last month, the yield curve has flattened modestly, with both short-term interest rates increasing and longer rates holding steady. One reason for noting this is that the slope of the yield curve 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 six recessions (as defined by the NBER ). Very flat yield curves preceded the previous two, and there have been two notable false positives: an inversion in late 1966 and a very flat curve in late 1998. More generally, though, a flat curve indicates weak growth, and conversely, a steep curve indicates strong growth. One measure of slope, the spread between 10-year bonds and 3-month T-bills, bears out this relation, particularly when real GDP growth is lagged a year to line up growth with the spread that predicts it.
The yield curve slope became somewhat flatter, with short rates moving up. The spread remains positive, with the 10-year rate moving up 1 basis point to 3.91 percent and the 3-month rate moving up 9 basis points to 1.86 percent (both for the week ending August 15). Standing at 205 basis points, the spread is just below the 213 basis points seen in July and the 218 basis points of June. Projecting forward using past values of the spread and GDP growth suggests that real GDP will grow at about a 3.0 percent rate over the next year. This remains on the high side of other forecasts.
While such an approach predicts when growth is above or below average, it does not do so well in predicting the actual number, especially in the case of recessions. Thus, it is sometimes preferable to focus on using the yield curve to predict a discrete event: whether or not the economy is in recession. Looking at that relationship, the expected chance of the economy being in a recession next August stands at 1.3 percent, just above June and July's 1.1 percent.
The probability of recession is below several recent estimates, and perhaps seems strange the in the midst of recent financial concerns. But one aspect of those concerns has been a flight to quality, which lowers Treasury yields. Also working to steepen the yield curve are the reductions in both the federal funds target rate and the discount rate by the Federal Reserve. Furthermore, the forecast is for where the economy will be next August, not earlier in the year.
To compare the 1.1 percent to some other probabilities, and learn more about different techniques of predicting recessions, head on over to the Econbrowser blog.
Of course, it might not be advisable to take this number 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. 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 Commentary “Does the Yield Curve Signal Recession?”