Chapter 18 - Spending, output, and fiscal policy. After completing this unit, you should be able to: Identify the key assumptions of the basic Keynesian model and explain how this affects firms' production decisions; discuss the determination of planned investment and aggregate consumption spending and how these concepts are used to develop a model of planned aggregate expenditure; analyze how an economy reaches short-run equilibrium in the basic Keynesian model, using both numbers and graphs, | Lecture Principles of economics 2e Chapter 18 - Robert H. Frank Ben S. Bernanke