The paper compares three versions of the Z-D model that diagrammatically describe Keynes's employment function. The paper also corrects Keynes's verbal description of the employment function in the General Theory. The papers comes to the conclusion that the three compared versions prove that it is possible to describe the employment function through a diagram based on the concept of effective demand and taking into account less restrictive assumptions than those assumed by Keynes.
Keynes; employment function; Z-D model; Principle of Effective Demand
