Google
Sunday 
August 16, 2026 

AmosWEB means Economics with a Touch of Whimsy!

AmosWEBWEB*pediaGLOSS*aramaECON*worldCLASS*portalQUIZ*tasticPED GuideXtra CrediteTutorA*PLS
AGGREGATE DEMAND CURVE: A graphical representation of the relation between aggregate expenditures on real production and the price level, holding all ceteris paribus aggregate demand determinants constant. The aggregate demand, or AD, curve is one side of the graphical presentation of the aggregate market. The other side is occupied by the aggregate supply curve (which is actually two curves, the long-run aggregate supply curve and the short-run aggregate supply curve). The negative slope of the aggregate demand curve captures the inverse relation between aggregate expenditures on real production and the price level. This negative slope is attributable to the interest-rate effect, real-balance effect, and net-export effect.

Visit the GLOSS*arama


INVESTMENT LINE:

A graphical depiction of the relation between investment expenditures by the business sector and the economy's aggregate level of income or production. This relation plays a key role in the study of Keynesian economics. A investment line is characterized by vertical intercept, which indicates autonomous investment, and slope, which is the marginal propensity to invest and indicates induced investment. The aggregate expenditures line used in Keynesian economics is derived by adding or stacking the investment line onto the consumption line, then adding government purchases and net exports to this stack.
The investment line, also termed propensity-to-invest line, shows the relation between investment expenditures by the business sector and aggregate income or production. The income and production measures most commonly used are national income and gross domestic product. The purpose of the investment line is to graphically illustrate the investment-income relation for the business sector, which is then integrated into the aggregate expenditures line used in Keynesian economics.

The investment line is commonly presented in one of two forms reflecting autonomous investment and induced investment. The simplest is a horizontal investment line, one with a zero slope, that illustrates autonomous investment. With a horizontal line, investment expenditures are constant for all levels of aggregate income or production, hence autonomous and unaffected by income. A more realistic investment line is positively sloped, indicating a degree of induced investment. In this case, the vertical intercept, or Y-intercept, of the investment line marks autonomous investment and the slope represents induced investment. Of no small importance, the slope of the investment line is also the marginal propensity to invest (MPI).

Investment Line
Investment Line

The horizontal red line, labeled I in the exhibit to the right, indicates investment that is completely autonomous. There is no induced investment indicated by this line. The slope of the investment line is zero (MPI = 0). The intercept of this horizontal line indicates autonomous investment, which is $2 trillion in this case.

An alternative investment line, one with induced investment, can be illustrated in the exhibit with a simple click of the [An Induced Line] button. The new red line, labeled I' in the exhibit, is positively sloped, indicating that a change in the level of income or production induces a change in investment expenditures.

This new investment line actually indicates both induced investment and autonomous investment. The slope is induced investment and the intercept is autonomous investment.

  • Slope: The slope of this new investment line is positive, but less than one. In this case the slope is equal to 0.10, a $1 change in aggregate income or production induces a $0.10 change in investment expenditures. This positive slope indicates induced investment. Moreover, the slope of the line is also the marginal propensity to invest (MPI).

  • Intercept: This new investment line, like the original line, intersects the vertical axis at a positive value of $2 trillion. And once again this indicates autonomous investment.

<= INVESTMENT EXPENDITURES DETERMINANTSINVESTMENT, PRODUCTION POSSIBILITIES =>


Recommended Citation:

INVESTMENT LINE, AmosWEB Encyclonomic WEB*pedia, http://www.AmosWEB.com, AmosWEB LLC, 2000-2026. [Accessed: August 16, 2026].


Check Out These Related Terms...

     | induced investment | autonomous investment | marginal propensity to invest | slope, investment line | intercept, investment line | consumption line | saving line | government purchases line | net exports line |


Or For A Little Background...

     | investment | investment expenditures | Keynesian economics | macroeconomics | business sector | national income | gross domestic product |


And For Further Study...

     | induced expenditures | autonomous expenditures | aggregate expenditures | aggregate expenditures line | derivation, consumption line | investment expenditures determinants | Keynesian model | Keynesian equilibrium | injections-leakages model | aggregate demand | paradox of thrift | fiscal policy | multiplier | investment, production possibilities | investment business cycles |


Search Again?

Back to the WEB*pedia


APLS

BLUE PLACIDOLA
[What's This?]

Today, you are likely to spend a great deal of time wandering around the downtown area trying to buy either galvanized steel storage shelves or a large green chalkboard shaped like the state of Maine. Be on the lookout for neighborhood pets, especially belligerent parrots.
Your Complete Scope

This isn't me! What am I?

In his older years, Andrew Carnegie seldom carried money because he was offended by its sight and touch.
"If I have ever made any valuable discoveries, it has been owing more to patient attention than to any other talent. "

-- Isaac Newton, mathematician, physicist

FTSE-100
Financial Times Stock Exchange 100 stock index (UK)
A PEDestrian's Guide
Xtra Credit
Tell us what you think about AmosWEB. Like what you see? Have suggestions for improvements? Let us know. Click the User Feedback link.

User Feedback



| AmosWEB | WEB*pedia | GLOSS*arama | ECON*world | CLASS*portal | QUIZ*tastic | PED Guide | Xtra Credit | eTutor | A*PLS |
| About Us | Terms of Use | Privacy Statement |

Thanks for visiting AmosWEB
Copyright ©2000-2026 AmosWEB*LLC
Send comments or questions to: WebMaster