So far, our discussion of budget deficits has been theoretical. Do the effects we have discussed occur in actual experience? There is a large empirical literature that looks for these effects. Unfortunately, this work has neither refuted the theories we have sketched nor convinced skeptics of their validity. The main obstacle to convincing empirical work is the identification problem. Countries do not run fiscal policies as controlled experiments; instead, policies change over time in response to changing economic circumstances. It is difficult to sort out the effects of budget deficits from their causes.
Nonetheless, it is useful to examine the U.S. experience over the past dozen years. Table 1 provides some summary statistics. While these data do not prove anything definitively, they show that the U.S. experience can be explained by conventional theories. The figures also offer a sense of the magnitudes involved.
As the top line of Table 1 shows, beginning in the early 1980s, the U.S. government switched from a policy of (inflation-adjusted) budget surpluses to budget deficits. Public saving fell by 2.4 percent of GDP. Rather than rising as one might expect, private saving rates fell slightly, suggesting that the increased impatience exhibited in fiscal policy also infected the private sector. National saving fell by about 2.9 percentage points.