 Macroeconomics grapples with the relations among economic aggregates, such as relations between the money supply and the rate of interest or the rate of growth, focusing especially on problems concerning the business cycle and the influence of monetary and fiscal policy on economic outcomes. Many mainstream economists would like to unify macroeconomics and microeconomics, but few economists are satisfied with the attempts that have been made to do so, especially via so called “representative agents” (Kirman 1992, Hoover 2001a). Macroeconomics is immediately relevant to economic policy and hence (and unsurprisingly) subject to much more heated (and politically-charged) controversy than microeconomics or econometrics. Schools of macroeconomics include Keynesians (and “new-Keynesians”), monetarists, “new classical economics” (rational expectations theory — Begg 1982, Carter and Maddock 1984, Hoover 1988, Minford and Peel 1983), and “real business cycle” theories (Kydland and Prescott 1991, 1994; Sent 1998).