It is generally recognized that, if a set of monetary and fiscal policy variables Granger-cause1 real economic variables, this does not imply that alternative deterministic rules for determining the values of these policy instruments will alter the joint density function of the real variables.2 It has, however, also been asserted that (letting X denote a (suitably restricted) vector of "real" economic aggregates, g a list of monetary and fiscal policy variables and E the mathematical expectation operator),