Surplus-Debt Regressions

Single-equation estimates of fiscal reaction functions, which relate primary surpluses to past debt-GDP ratios and control variables, are subject to potentially serious simultaneity bias that can produce misleading inferences about fiscal behavior. Biases arise from failure to model the general equilibrium relationships between government debt and surpluses, relationships that bring in the forward-looking nature of nominal debt valuation and the role of monetary policy in that valuation.