What is meant by the term "expenditure multiplier"?

Question

What is meant by the term "expenditure multiplier"?

Answer 1

The expenditure multiplier measures the rate of change in output due to a change in autonomous spending.

Autonomous spending is aggregate spending unrelated to income. Investment, government purchases, net exports, and part of consumer spending are all treated as autonomous in very simple Keynesian cross models.

The definition of the expenditure multiplier is:

Change in equilibrium Gross Domestic Product divided by change in autonomous spending

The formula for the expenditure multiplier is:  

1/(1-Slope of the Aggregate Expenditure function)