Debt and the U.S. Great Moderation

During the Great Moderation, borrowing by the U.S. nonfinancial sector structurally exceeded GDP growth. Using flow-of-fund data, we test the hypothesis that this measure of debt buildup was leading to lower output volatility. We estimate univariate GARCH models in order to obtain estimates for the volatility of output growth. We use this obtained volatility in a VAR model with excess credit growth and control variables (interest rate and inflation) over two periods, 1954-1978 (before the Great Moderation) and 1984-2008 (during the Great Moderation). We so test whether the relation between excess credit growth and GDP volatility changed between the two periods, controlling for the stance of monetary policy, for inflation, and for the endogeneity of credit to growth (as well as for other endogeneities). Results from Granger causality tests, impulse response functions and forecast error variance decompositions suggest that changes in our ‘excess credit growth’ measure of debt in the nonfinancial sector were among the causal factors of the decline in output volatility during the Great Moderation. We discuss implications.