Summary

As a quick summary, we can say that:

Fiscal policy is more effective the flatter is the LM curve and the steeper is the IS curve.

Monetary policy is more effective the steeper is the LM curve and the flatter is the IS curve.

The condition that makes monetary policy most effective makes fiscal policy least effective. The reason for the difference is the differing role of interest rate plays in transmitting the effects of
monetary and fiscal policy .