Diminishing returns - Wikipedia Diminishing returns This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. ( August 2011 ) Economics A supply and demand diagram, illustrating the effects of an increase in demand Index Outline Category History Types Classification History of economics Economic history ( academic study ) Schools of economics Microeconomics Macroeconomics Methodology Heterodox economics JEL classification codes Concepts Theory Techniques Econometrics Economic growth Economic system Experimental economics Mathematical economics Game theory Post-scarcity Market National accounting By application Agricultural Behavioral Business Computational Cultural Demographic Development Digitization Ecological Education Engineering Environmental Evolutionary Expeditionary Geography Health Industrial organization Information International Knowledge Labour Law Managerial Monetary / Financial Natural resource Organizational Personnel Public / Welfare economics Regional Rural Service Social Urban Welfare Lists Economists Publications ( journals ) Glossary Glossary of economics Business and economics portal In economics, diminishing returns is the decrease in the marginal ( incremental ) output of a production process as the amount of a single factor of production is incrementally increased, while the amounts of all other factors of production stay constant. The law of diminishing returns states that in all productive processes, adding more of one factor of production, while holding all others constant ( `` ceteris paribus '' ), will at some point yield lower incremental per - unit returns. The law of diminishing returns does not imply that adding more of a factor will decrease the total production, a condition known as negative returns, though in fact this is common. A common example is adding more people to a job, such as the assembly of a car on a factory floor. At some point, adding more workers causes problems such as workers getting in each other 's way or frequently finding themselves waiting for access to a part. In all of these processes, producing one more unit of output per unit of time will eventually cost increasingly more due to inputs being used less effectively. Another well - studied example is throwing more headcount at software development, yielding Brooks 's law. The law of diminishing returns is a fundamental principle of economics. It plays a central role in production theory. Contents 1 History 2 Diminishing marginal returns 3 Returns and costs 4 See also 5 References 6 Sources History This section needs expansion. You can help by adding to it. ( December 2009 ) The concept of diminishing returns can be traced back to the concerns of early economists such as Johann Heinrich von Thünen, Jacques Turgot, Adam Smith, James Steuart, Thomas Robert Malthus, and David Ricardo. However, classical economists such as Malthus and Ricardo attributed the successive diminishment of output to the decreasing quality of the inputs. Neoclassical economists assume that each `` unit '' of labor is identical. Diminishing returns are due to the disruption of the entire productive process as additional units of labor are added to a fixed amount of capital. The law of diminishing returns remains an important consideration in farming. Diminishing marginal returns As labor usage increases from L to L, total output ( measured vertically in the top graph ) increases by the amount shown. But if labor usage is increased by the same amount again, output goes up by less, implying diminishing marginal returns to the use of labor as an input. The marginal product of labor ( measured vertically in the bottom graph ) is diminishing everywhere to the right of point A. This article may lack focus or may be about more than one topic. Please help improve this article, possibly by splitting the article and / or by introducing a disambiguation page, or discuss this issue on the talk page. ( September 2011 ) The defining feature of diminishing marginal returns is that as total investment increases, the total return on investment as a proportion of the total investment ( the average product or return ) decreases. Suppose, for example, that 1 kilogram of seed applied to a certain plot of land produces one ton of crop, that 2 kg of seed produces 1.5 tons, and that 3 kg of seed produces 1.75 tons. In formulaic terms, the i ( displaystyle ( i ) ) th kg of seeds produces 1 2 i − 1 ( displaystyle ( \frac ( 1 ) ( 2 ^ ( i - 1 ) ) ) ) additional tons of crop. The return from investing the first kilogram is 1 t / kg. When 2 kg of seed is invested, the return is 1.5 / 2 = 0.75 t / kg, and when 3 kg is invested, the return is 1.75 / 3 = 0.58 t / kg. In formulaic terms, for this example, the diminished marginal return is : D = 1 X ∑ i = 1 X 1 2 i − 1 ( displaystyle ( \text ( D ) ) = ( \frac ( 1 ) ( X ) ) sum _ ( i = 1 ) ^ ( X ) ( \frac ( 1 ) ( 2 ^ ( i - 1 ) ) ) ) where X ( displaystyle ( \text ( X ) ) ) = seed in kilograms, and 1 2 i − 1 ( displaystyle ( \frac ( 1 ) ( 2 ^ ( i - 1 ) ) ) ) = additional crop yield in tons, for the i ( displaystyle ( i ) ) th kilogram of seed. Substituting 3 for X ( displaystyle ( \text ( X ) ) ) and expanding yields : D = 1 3 ∑ i = 1 3 1 2 i − 1 ( displaystyle ( \text ( D ) ) = ( \frac ( 1 ) ( 3 ) ) sum _ ( i = 1 ) ^ ( 3 ) ( \frac ( 1 ) ( 2 ^ ( i - 1 ) ) ) ) = 1 3 ⋅ ( 1 2 1 − 1 + 1 2 2 − 1 + 1 2 3 − 1 ) ( displaystyle = ( \frac ( 1 ) ( 3 ) ) cdot left ( ( \frac ( 1 ) ( 2 ^ ( 1 - 1 ) ) ) + ( \frac ( 1 ) ( 2 ^ ( 2 - 1 ) ) ) + ( \frac ( 1 ) ( 2 ^ ( 3 - 1 ) ) ) \right ) ) = 1 3 ⋅ ( 1 2 0 + 1 2 1 + 1 2 2 ) ( displaystyle = ( \frac ( 1 ) ( 3 ) ) cdot left ( ( \frac ( 1 ) ( 2 ^ ( 0 ) ) ) + ( \frac ( 1 ) ( 2 ^ ( 1 ) ) ) + ( \frac ( 1 ) ( 2 ^ ( 2 ) ) ) \right ) ) = 1 3 ⋅ ( 1 1 + 1 2 + 1 4 ) = 1.75 3 ( displaystyle = ( \frac ( 1 ) ( 3 ) ) cdot left ( ( \frac ( 1 ) ( 1 ) ) + ( \frac ( 1 ) ( 2 ) ) + ( \frac ( 1 ) ( 4 ) ) \right ) = ( \frac ( 1.75 ) ( 3 ) ) ) = 0.58 3  ̄ t / kg ( displaystyle = 0.58 ( overline ( 3 ) ) ( \text ( t / kg ) ) ) Another example is a factory that has a fixed stock of capital, or tools and machines, and a variable supply of labor. As the firm increases the number of workers, the total output of the firm grows but at an ever - decreasing rate. This is because after a certain point, the factory becomes overcrowded and workers begin to form lines to use the machines. The long - run solution to this problem is to increase the stock of capital, that is, to buy more machines and to build more factories. Returns and costs There is an inverse relationship between returns of inputs and the cost of production. Suppose that a kilogram of seed costs one dollar, and this price does not change. Although there are other costs, assume they do not vary with the amount of output and are therefore fixed costs. One kilogram of seeds yields one ton of crop, so the first ton of the crop costs one dollar to produce. That is, for the first ton of output, the marginal cost of the output is $1 per ton. If there are no other changes, then if the second kilogram of seeds applied to land produces only half the output of the first, the marginal cost would equal $1 per half ton of output, or $2 per ton. Similarly, if the third kilogram of seeds yields only a quarter ton, then the marginal cost equals $1 per quarter ton or $4 per ton. Thus, diminishing marginal returns imply increasing marginal costs and rising average costs. Cost can also be measured in terms of opportunity cost. In this case the law also applies to societies -- the opportunity cost of producing a single unit of a good generally increases as a society attempts to produce more of that good. This explains the bowed - out shape of the production possibilities frontier. See also Economics portal Diminishing marginal utility, also not to be mistaken for ' diminishing returns ' Diseconomies of scale, does not assume fixed inputs, thus differing from ' diminishing returns ' Economies of scale Learning curve and Experience curve effects Liebig 's Law of the minimum Marginal value theorem Opportunity cost Returns to scale Pareto principle Submodular set function Tendency of the rate of profit to fall References ^ Jump up to : Samuelson, Paul A. ; Nordhaus, William D. ( 2001 ). Microeconomics ( 17th ed. ). McGraw - Hill. p. 110. ISBN 0071180664. Jump up ^ George, Henry. The Science of Political Economy. New York : Robert Schalkenbach Foundation. Jump up ^ Encyclopædia Britannica. Encyclopædia Britannica, Inc. 26 Jan 2013. ISBN 9781593392925. Jump up ^ Smith, Adam. The wealth of nations. Thrifty books. ISBN 9780786514854. Sources Case, Karl E. ; Fair, Ray C. ( 1999 ). Principles of Economics ( 5th ed. ). Prentice - Hall. ISBN 0 - 13 - 961905 - 4. 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Question: when does law of diminishing returns set in
Answer: in all productive processes, adding more of one factor of production, while holding all others constant ("ceteris paribus"), will at some point yield lower incremental per-unit returns