To get a better impression of the quantitative relationships in/of the various channels of macroeconomic models, E. Kuh, J. Neese, and P. Hollinger (1982, 1985) introduced the technique of systematic parameter perturbation. This technique is applied to the RWI-business cycle model, a medium sized (41 stochastic equations, 86 definitions), quarterly macroeconometric model for the FRG. The evaluation of the results concentrates on (1) the sensitivity of the model to parameter perturbations in general, and to (2) the sensitivity of policy goal variables in particular. The findings show that in the model the number of important within-block and between-block relationships is much smaller than suggested by usual incidence matrices, providing additional evidence for H. Simon's (1981) "empty world hypothesis." Citation Copyright 1992 by Kluwer Academic Publishers.