Final answer:
Keynesian economists emphasize the demand side of the economy due to the assumption that prices and wages are 'sticky downward', which can cause unemployment and prevent an economy from reaching full employment.
Step-by-step explanation:
The key side of the economy for Keynesian economists is the demand side. This emphasis is based on the assumption that prices and wages are "sticky downward," meaning that they do not adjust quickly downwards in the face of reduced demand. This stickiness can lead to persistent unemployment during economic downturns as wages do not decrease to meet the lower level of demand, implying that production and employment adjust instead. Keynesian analysis highlights the macroeconomic externality of wage and price stickiness, with a particular concern for how it prevents the economy from reaching full employment and potential GDP. The expenditure multiplier is also central to Keynesian economics, which suggests that a change in autonomous expenditure leads to a more than proportionate change in G