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Sunk costs

In the budget constraint framework, all decisions involve what will happen next: that is, what quantities of goods will you consume, how many hours will you work, or how much will you save. These decisions do not look back to past choices. Thus, the budget constraint framework assumes that sunk costs    , which are costs that were incurred in the past and cannot be recovered, should not affect the current decision.

Consider the case of Selena, who pays $8 to see a movie, but after watching the film for 30 minutes, she knows that it is truly terrible. Should she stay and watch the rest of the movie because she paid for the ticket, or should she leave? The money she spent is a sunk cost, and unless the theater manager is feeling kindly, Selena will not get a refund. But staying in the movie still means paying an opportunity cost in time. Her choice is whether to spend the next 90 minutes suffering through a cinematic disaster or to do something—anything—else. The lesson of sunk costs is to forget about the money and time that is irretrievably gone and instead to focus on the marginal costs and benefits of current and future options.

For people and firms alike, dealing with sunk costs can be frustrating. It often means admitting an earlier error in judgment. Many firms, for example, find it hard to give up on a new product that is doing poorly because they spent so much money in creating and launching the product. But the lesson of sunk costs is to ignore them and make decisions based on what will happen in the future.

From a model with two goods to one of many goods

The budget constraint diagram containing just two goods, like most models used in this book, is not realistic. After all, in a modern economy people choose from thousands of goods. However, thinking about a model with many goods is a straightforward extension of what we discussed here. Instead of drawing just one budget constraint, showing the tradeoff between two goods, you can draw multiple budget constraints, showing the possible tradeoffs between many different pairs of goods. Or in more advanced classes in economics, you would use mathematical equations that include many possible goods and services that can be purchased, together with their quantities and prices, and show how the total spending on all goods and services is limited to the overall budget available. The graph with two goods that was presented here clearly illustrates that every choice has an opportunity cost, which is the point that does carry over to the real world.

Key concepts and summary

Economists see the real world as one of scarcity: that is, a world in which people’s desires exceed what is possible. As a result, economic behavior involves tradeoffs in which individuals, firms, and society must give up something that they desire to obtain things that they desire more. Individuals face the tradeoff of what quantities of goods and services to consume. The budget constraint, which is the frontier of the opportunity set, illustrates the range of choices available. The slope of the budget constraint is determined by the relative price of the choices. Choices beyond the budget constraint are not affordable.

Opportunity cost measures cost by what is given up in exchange. Sometimes opportunity cost can be measured in money, but it is often useful to consider time as well, or to measure it in terms of the actual resources that must be given up.

Most economic decisions and tradeoffs are not all-or-nothing. Instead, they involve marginal analysis, which means they are about decisions on the margin, involving a little more or a little less. The law of diminishing marginal utility points out that as a person receives more of something—whether it is a specific good or another resource—the additional marginal gains tend to become smaller. Because sunk costs occurred in the past and cannot be recovered, they should be disregarded in making current decisions.


Use this information to answer the following 4 questions: Marie has a weekly budget of $24, which she likes to spend on magazines and pies.

If the price of a magazine is $4 each, what is the maximum number of magazines she could buy in a week?

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If the price of a pie is $12, what is the maximum number of pies she could buy in a week?

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Draw Marie’s budget constraint with pies on the horizontal axis and magazines on the vertical axis. What is the slope of the budget constraint?

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What is Marie’s opportunity cost of purchasing a pie?

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Bureau of Labor Statistics, U.S. Department of Labor. 2015. “Median Weekly Earnings by Educational Attainment in 2014.” Accessed March 27, 2015. http://www.bls.gov/opub/ted/2015/median-weekly-earnings-by-education-gender-race-and-ethnicity-in-2014.htm.

Robbins, Lionel. An Essay on the Nature and Significance of Economic Science . London: Macmillan. 1932.

United States Department of Transportation. “Total Passengers on U.S Airlines and Foreign Airlines U.S. Flights Increased 1.3% in 2012 from 2011.” Accessed October 2013. http://www.rita.dot.gov/bts/press_releases/bts016_13

Questions & Answers

using the graph illustrate all the types of elascity
Umar Reply
Given the budget deficit in recent years, some economists have argued that by adjusting Social Security (SSNIT) payments for inflation using the CPI, SSNIT is overpaying recipients. Discuss the argument being made, and do you agree or disagree with it?
distinguish between increase in demand curve and extenaion in demamd curve
Farhan Reply
what are the shapes of an indifference curve?
Ovensi Reply
division of labour is simply the breaking of job functions so that each individual is engage to one set or the other for easy delivery
What is division of labor
peter Reply
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what are the sources of monopoly power?
Winnerman Reply
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political power and influence in monetary institutions
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SHAH Reply
the situation in which elements of monopoly ( R&D, EOS and stability of prices etc.) allow individual producers or consumers to exercise some control over market prices
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Sowmya Reply
where p is less than avc
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olaleye Reply
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Micro-economics refers to the branch of economics which deals with smaller unit or element of the economy.
or Is the study of individual economic unit in a economy..
micro economis is the studay of how Households and firms make decision and they interecr it.
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Imran Reply
financial intermediaries are those who are link between borrowers and lenders for.eg bank... Bank is a financial intermediary
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sorry it's...Law of diminishing marginal utility
demand for commodities that posses identical utilities? The commodities having identical utilities are perfect substitutes...and the demand for such type of commodities is called "Competitive Demand".
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the central bank may lend some money to banks if necessary
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is the study of how societies allocate and manage their scare resources
What is populatiin
Azer Reply
Population is a number of people living in a particular area within a particular time
Population is the number of people living in a particular geographical area within a particular time
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what is demand schedule
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is a tabular representation of the quantity demanded of a particular product at a particular price over a given period of time
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What is Monetary Mass
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