Macroeconomic Effects From Government Purchases and Taxes *

For U.S. annual data that include WWII, the estimated multiplier for defense spending is 0.6-0.7 at the median unemployment rate. There is some evidence that this multiplier rises with the extent of economic slack and reaches 1.0 when the unemployment rate is around 12%. Multipliers for non-defense purchases cannot be reliably estimated from U.S. macroeconomic time series because of the lack of good instruments. Since the defense-spending multiplier is typically less than one, greater spending tends to crowd out other components of GDP. The largest effects are on private investment, but non-defense purchases and net exports tend also to fall. The response of private consumer expenditure differs insignificantly from zero. For samples that begin in 1950, increases in average marginal income-tax rates (measured by a newly constructed time series) have a significantly negative effect on real GDP. We lack reliable statistical evidence on how this response divides up between substitution effects from changes in tax rates versus income effects from changes in government revenue.