World Library  
Flag as Inappropriate
Email this Article

Consumption function

Article Id: WHEBN0000736018
Reproduction Date:

Title: Consumption function  
Author: World Heritage Encyclopedia
Language: English
Subject: Consumption (economics), Induced consumption, Consumer behaviour, Robertson lag, Fundamental psychological law
Collection: MacRoeconomics
Publisher: World Heritage Encyclopedia

Consumption function

In economics, the consumption function describes a relationship between consumption and disposable income.[1] Algebraically, this means C = f(Y_{d}) where f \colon \mathbb{R} \to \mathbb{R} is a function that maps levels of disposable income Y_{d}—income after government intervention, such as taxes or transfer payments—into levels of consumption C. The concept is believed to have been introduced into macroeconomics by John Maynard Keynes in 1936, who used it to develop the notion of a government spending multiplier.[2] Its simplest form is the linear consumption function used frequently in simple Keynesian models:[3]

C = a + b \times Y_{d}

where a is the autonomous consumption that is independent of disposable income; in other words, consumption when income is zero. The term b \times Y_{d} is the induced consumption that is influenced by the economy's income level. The parameter b is known as the marginal propensity to consume, i.e. the increase in consumption due to an incremental increase in disposable income, since \partial C / \partial Y_{d} = b. Geometrically, b is the slope of the consumption function. One of the key assumptions of Keynesian economics is that this parameter is positive but smaller than one, i.e. b \in (0,1).[4]

Criticism of the simplicity and irreality of this assumption lead to the development of Milton Friedman's permanent income hypothesis, and Richard Brumberg and Franco Modigliani's life-cycle hypothesis. But none of them developed a definitive consumption function. Friedman, although he got the Nobel prize for his book A Theory of the Consumption Function (1957), presented several different definitions of the permanent income in his approach, making it impossible to develop a more sophisticated function. Modigliani and Brumberg tried to develop a better consumption function using the income got in the whole life of consumers, but them and their followers ended in a formulation lacking economic theory and therefore full of proxies that do not account for the complex changes of today's economic systems.

Until recently, the three main existing theories, based on the income dependent Consumption Expenditure Function pointed by Keynes in 1936, were Duesenberry's (1949) relative consumption expenditure,[5] Modigliani and Brumberg's (1954) life-cycle income, and Friedman's (1957) permanent income.[6]

Some new theoretical works are based, following Duesenberry's one, on behavioral economics and suggest that a number of behavioural principles can be taken as microeconomic foundations for a behaviorally-based aggregate consumption function.[7]

See also


Further reading

  • (Undergraduate level discussion of the subject.)
  • (Graduate level discussion of the subject.)

External links

  • An essay examining the strengths and weaknesses of Keynes's theory of consumption
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.

Copyright © World Library Foundation. All rights reserved. eBooks from World Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.