Microeconomics

Microeconomics (literally, very small economics) is a social science which involves study of the economic distribution of production and income among individual consumers, firms, and industries. (Contrast macroeconomics.) It considers individuals both as suppliers of labour and capital and as the ultimate consumers of the final product. It analyzes firms both as suppliers of products and as consumers of labour and capital. It is the study of the behavior of individuals and firms that are using scarce resources. Scarcity refers to the fact that none of us as individuals or companies, can "have it all"—unlimited land, capital, labour, etc.

One of the goals of the field of microeconomics is to analyze mechanisms and market forces that establish relative prices amongst goods and services and allocate society's resources amongst their many alternative uses.

Assumptions and definitions

The theory of supply and demand usually assumes that markets are perfectly competitive. This implies that there are many buyers and sellers in the market and none of them have the capacity to significantly influence prices of goods and services. In many real-life transactions, the assumption fails because some individual buyers or sellers or groups of buyers or sellers do have the ability to influence prices. Quite often a sophisticated analysis is required to understand the demand-supply equation of a good. However, the theory works well in simple situations.

Mainstream economics does not assume a priori that markets are preferable to other forms of social organization. In fact, much analysis is devoted to cases where so-called market failures lead to resource allocation that is suboptimal by some standard. In such cases, economists may attempt to find policies that will avoid waste; directly by government control, indirectly by regulation that induces market participants to act in a manner consistent with optimal welfare, or by creating "missing" markets to enable efficient trading where none had previously existed. This is studied in the field of collective action.

This page deals with the various forms of economic surplus, including producer, consumer, government, and social/total surplus. For information about a budget surplus, see budget deficit.

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If the government intervenes, using, for example, a tax or a subsidy, then the graph of supply and demand becomes more complicated and will also include an area that represents government surplus.

Combined, the consumer surplus, the producer surplus, and the government surplus (if present) make up the social surplus or the total surplus. Total surplus is the primary measure used in Welfare Economics to evaluate the efficiency of a proposed policy.

A basic technique of bargaining for both parties is to pretend that their surplus is less than it really is: sellers may argue that the price they asks hardly leaves them any profit, while customers may play down how eager they are to have the article.

In national accounts, operating surplus is roughly equal to distributed and undistributed pre-tax profit income, net of depreciation.

In heterodox economics, the economic surplus denotes the total income which the ruling class derives from its ownership of society's (productive) assets, which is either reinvested or spent on consumption.

In Marxian economics, the term surplus may also refer to surplus value and surplus labour.

The demand for various commodities by individuals is generally thought of as the outcome of a utility-maximizing process. The interpretation of this relationship between price and quantity demanded of a given good is that, given all the other goods and constraints, this set of choices is that one which makes the consumer happiest.

Aggregate, or market, demand curves represent the sum of these individual demand curves. An important question is whether market demand curves can also be thought of as being generated by a utility-maximization process. Does the aggregated demand curve show how to optimise the total utility (happiness) of society? Does it show how to optimise something else? The answer to these questions is no; market demand curves generally have no utility interpretation.

Moreover, even if market demand curves could mathematically be rationalized by a utility function; they still cannot be economically rationalized as generating an overall welfare index. There are several reasons for this

1. Each person's individual total utility gleaned from purchases depends on the size of his or her budget, but the distribution of wealth (and thus her budget) is a separate (free) variable in the aggregation. In other words, changing the distribution of wealth (such as giving needy people more resources) will produce a different total for society's utility.
2. Each person's demand curve is a function of his or her budget, so that if the distribution of wealth changes (by changing the distribution of prices and thus salaries, and so on), all of the individual demand curves change. The aggregate effect of such a change is not simple unless all the consumers have wealth-independent consumption patterns --- that is, unless the pauper and the billionaire spend the same fraction of their budgets on each item.

Markets cannot be claimed to select an optimum in the sense of the greatest total utility of society; indeed, there is not even general agreement on how total utility should be defined. However, under strictly competitive conditions, market outcomes do represent a Pareto optimum.

It has been known since at least 1953 (Gorman, W.M., Community Preference Fields, Econometrica, 21: 63-80) and 1982 (Shafer, W. and Sonnenschein, H., Market demand and excess demand functions, in K. J. Arrow and M. D. Intriligator (eds), Handbook of Mathematical Economics (Vol. II), North-Holland, Amsterdam) that no reasonable assumptions can circumvent these problems.

Income, generally defined, is the money that is received as a result of the normal business activities of an individual or a business. For example, most individuals' income is the money they receive from their regular paychecks.

In business and accounting, income (also known as profit or earnings) is, more specifically, the amount of money that a company earns after paying for all its costs. To calculate a company's income, it starts with its amount of revenue, deducts all costs, including such things as employees' salaries and depreciation, and the number that results is its income, which may be a negative number. This money is typically reinvested in the business, paid in corporate tax and used to pay the owners (the shareholders) a dividend.

All public companies are required to provide financial statements on a quarterly basis. The statement of income is an important part of this. Some companies also provide a more rosy financial report of their income, with pro forma reporting, or, EBITDA reporting. Pro forma income is an estimate of how much the company would have earned without including the negative effect of exceptional "one-time events", supposedly in order to show investors how much money the company would have made under normal circumstances if these exceptional, one-time events had not occurred. Critics charge that, in most cases, the "one-time events" are normal business events, such as an acquisition of another company or a write off of a cancelled project or division, and that pro forma reporting is an attempt to mislead investors by painting a rosy financial picture. Besides that, when discussing results with analysts and shareholders CEOs and CFOs have a tendency to do even more "hypothetical accounting". EBITDA stands for "earnings before interest, taxes, depreciation, and amortisation", and is also criticised for being an attempt to mislead investors. Warren Buffett has criticised EBITDA reporting, famously asking, "Does management think the tooth fairy pays for capital expenditures?"

It is common for some other companies, such as real estate investment trusts, to present reports using a standard called FFO, or funds from operations. Like EBITDA reporting, FFO ignores depreciation and amortization. This is widely accepted in the industry, as real estate values tend to increase rather than decrease over time, and many data sites report earnings per share data using FFO.

In economics, income is the constraint to unlimited consumer purchases. Consumers can purchase a limited number of goods. The basic equation for this is I = Px × x + Py × y, where Px is the price of good x, x is the quantity of good x, and I is the income (Py and y are similar to Px and x). If you need to examine more than two goods, you can add more on. This equation tells us two things. First, if you buy one more of good x, you get Px/Py less of good y. Here, Px/Py is known as the rate of substitution. Secondly, if the price of x changes, then the rate of substitution changes. This causes demand curves to slope down.

The distribution of income within a society can be measured by the Lorenz curve and the Gini coefficient.

National income, measured by statistics such as the Net National Income (NNI), measures the total income of all individuals in the economy. For more information see measures of national income and output.

In economics, profit maximization is the process by which a firm determines the price and output level that returns the greatest profit. There are several approaches to this problem. The total revenue -- total cost method relies on the fact that profit equals revenue minus cost, and the marginal revenue -- marginal cost method is based on the fact that total profit in a perfectly competitive market reaches its maximum point where marginal revenue equals marginal cost.

Basic Definitions

Any costs incurred by a firm may be classed into two groups: fixed cost and variable cost. Fixed costs are incurred by the business at any level of output, including none. These may include equipment maintenance, rent, wages, and general upkeep. Variable costs change with the level of output, increasing as more product is generated. Materials consumed during production often have the largest impact on this category. Fixed cost and variable cost, combined, equal total cost.

Revenue is the total amount of money that flows into the firm. This can be from any source, including product sales, government subsidies, venture capital and personal funds.

Average cost and revenue are defined as the total cost or revenue divided by the amount of units output. For instance, if a firm produced 400 units at a cost of 20000 USD, the average cost would be 50 USD.

Marginal cost and revenue, depending on whether the calculus approach is taken or not, are defined as either the change in cost or revenue as each additional unit is produced, or the derivative of cost or revenue with respect to quantity output. For instance, taking the first definition, if it costs a firm 400 USD to produce 5 units and 480 USD to produce 6, the marginal cost of the sixth unit is approximately 80 dollars, although this is more accurately stated as the marginal cost of the 5.5th unit due to linear interpolation. Calculus is capable of providing more accurate answers if regression equations can be provided.

Total Cost-Total Revenue Method

To obtain the profit maximizing output quantity, we start by recognizing that profit is equal to total revenue minus total cost. Given a table of costs and revenues at each quantity, we can either compute equations or plot the data directly on a graph. Finding the profit-maximizing output is as simple as finding the output at which profit reaches its maximum. That is represented by output Q in the diagram.

Profit Maximization - The Totals Approach

There are two graphical ways of determining that Q is optimal. Firstly, we see that the profit curve is at its maximum at this point (A). Secondly, we see that at the point (B) that the tangent on the total cost curve (TC) is parallel to the total revenue curve (TR), the surplus of revenue net of costs (B,C) is the greatest. Because total revenue minus total costs is equal to profit, the line segment C,B is equal in length to the line segment A,Q.

Computing the price at which to sell the product requires knowledge of the firm's demand curve. The price at which quantity demanded equals profit-maximizing output is the optimum price to sell the product.

Marginal Cost-Marginal Revenue Method

If total revenue and total cost figures are difficult to procure, this method may also be used. For each unit sold, marginal profit equals marginal revenue minus marginal cost. Then, if marginal revenue is greater than marginal cost, marginal profit is positive, and if marginal revenue is less than marginal cost, marginal profit is negative. When marginal revenue equals marginal cost, marginal profit is zero. Since total profit increases when marginal profit is positive and total profit decreases when marginal profit is negative, it must reach a maximum where marginal profit is zero - or where marginal cost equals marginal revenue. This intersection of marginal revenue (MR) with marginal costs (MC) is shown in the next diagram as point A. If the industry is competitive (as is assumed in the diagram), the firm faces a demand curve (D) that is identical to its Marginal revenue curve (MR), and this is a horizontal line at a price determined by industry supply and demand. Average total costs are reprsented by curve ATC. Total economic profits are represented by area P,A,B,C. The optimum quantity (Q) is the same as the optimum quantity (Q) in the first diagram.

Profit Maximization - The Marginal Approach

If the firm is operating in a non-competitive market, minor changes would have to be made to the diagrams.

Modes of Operation

It is assumed that all firms are following rational decision-making, and will produce at the profit-maximizing output. Given this assumption, there are four categories in which a firm's profit may be considered.

A firm is said to be making an economic profit when its average total cost is less than the price of the product at the profit-maximizing output. The economic profit is equal to the quantity output multiplied by the difference between the average total cost and the price.

A firm is said to be making a normal profit when its economic profit equals zero. This occurs where average total cost equals price at the profit-maximizing output.

If the price is between average total cost and average variable cost at the profit-maximizing output, then the firm is said to be in a loss-minimizing condition. The firm should still continue to produce, however, since its loss would be larger if it was to stop producing. By continuing production, the firm can offset its variable cost and at least part of its fixed cost, but by stopping completely it would lose equivalent of its entire fixed cost.

If the price is below average variable cost at the profit-maximizing output, the firm is said to be in shutdown. Losses are minimized by not producing at all, since any production would not generate returns significant enough to offset any fixed cost and part of the variable cost. By not producing, the firm loses only its fixed cost.

In economics, a market failure is a situation in which markets do not efficiently organize production or allocate goods and services to consumers (for example, a failure to allocate goods in a way some see as socially or morally preferable). To economists, the term would normally be applied to situations where the inefficiency is particularly dramatic, or when it is suggested that non-market institutions would provide a more desirable result. On the other hand, to many, market failures are situations where market forces do not serve the perceived "public interest". Here, the focus is on the economists' theories of market failure.

Economists use model-like theorems to explain or understand such cases. The two main reasons that markets fail are:

• the inadequate expression of costs or benefits in prices and thus into microeconomic decision-making in markets.
• sub-optimal market structures

In economics, information asymmetry occurs when one party to a transaction has more or better information than the other party. (It has also been called asymmetrical information and markets with asymmetrical information). Typically it is the seller that knows more about the product than the buyer, however, it is possible for the reverse to be true: for the buyer to know more than the seller.

Examples of situations where the seller usually has better information than the buyer are numerous but include used-car salespeople, stockbrokers, real estate agents, and life insurance transactions.

Examples of situations where the buyer usually has better information than the seller include estate sales as specified in a last will and testament.

This situation was first described by Kenneth J. Arrow in a seminal article on health care in 1963 entitled "Uncertainty and the Welfare Economics of Medical Care," in the American Economic Review.

George Akerlof later used the term asymmetric information in his 1970 work The Market for Lemons. He also noticed that, in such a market, the average value of the commodity tends to go down, even for those of perfectly good quality. It is even possible for the market to decay to the point of nonexistence.

Because of information asymmetry, unscrupulous sellers can "spoof" items (like software or computer games) and defraud the buyer. As a result, many people not willing to risk getting ripped off will avoid certain types of purchases, or will not spend as much for a given item.

Cost of Taking an Opportunity

The simplest way to estimate the opportunity cost of any single economic decision is to consider, "What is the next best alternative choice that could be made?" (This is even though most economic decisions involve multiple alternatives.) The opportunity cost of paying for college this semester could be the ability to make car payments. The opportunity cost of a vacation in the Bahamas could be the down payment money for a house.

Note that opportunity cost is not the sum of the available alternatives, but rather of benefit of the best alternative of them. The opportunity cost of the city's decision to build the hospital on its vacant land is the loss of the land for a sporting center, or the inability to use the land for a parking lot, or the money that could have been made from selling the land, or the loss of any of the various other possible uses -- but not all of these in aggregate.

It is important, as individuals and as societies, to compare the opportunity costs associated with various courses of action. However, some opportunities may be difficult to compare along all relevant dimensions.

Economists often try to use the market price of each alternative to measure opportunity cost. This method, however, presents a considerable difficulty, since many alternatives do not have a market price. It is very difficult to agree on a way to place a dollar value on a wide variety of intangible assets. How does one calculate the cost in dollars, pounds, euros, or yen for the loss of clean air, or the loss of seaside views, or the loss of pedestrian access to a shopping center, or the loss of an untouched virgin forest? Since their costs are difficult to quantify, intangible values associated with opportunity cost can easily be overlooked or ignored.

To overcome this difficulty, economists have identified certain opportunity costs as spillover costs (or external costs). If a chemical producer dumps its waste products into a river, the company has effectively shifted part of the cost of its production onto those living downstream who like to fish. If a billboard company blocks the seaside view of passers-by, some of its gain in advertising revenue is being paid by the passers-by who enjoy natural vistas, instead of by the company's advertisers.

Typically, spillover costs are imposed by a narrower group (often called a special interest group) which benefits more quantifiably and more concretely, and they are borne by a wider group -- perhaps even the public at large -- which pays less quantifiably and less concretely. For this reason, spillover costs are most often controlled by politics and government regulation rather than by markets. Regulations against pollution and building codes restricting billboard locations are examples.

Special interest groups, with a particular political or financial gain in mind, usually find incentives to underestimate or ignore the opportunity costs associated with their activities or agendas (especially when the opportunity costs are spillover costs, that can be imposed upon others), but at times such groups find incentives to overestimate them.

Another difficulty in fixing opportunity cost exists on the macroeconomic level, and is empirical in nature. Discovering the real effect of a change in production of butter specific to the production of guns in an economy as large and multifarious as, say, that of the United States, would be nightmarishly complex.

For that reason, opportunity cost is usually figured within some specific budget of resources. For example, "If the state spends $200 million more on highways it will have $200 million less to spend on schools." Or, "If our company invests $10 million in R+D, it can't give a $1 million Christmas bonus to each of its top ten executives." Or, "If I buy fifty lottery tickets, I won't have these two twenties and one ten left in my wallet for groceries."

Although opportunity cost can be hard to quantify, its effect is universal and very real on the individual level. The principle behind the economic concept of opportunity cost applies to all decisions, not just economic ones. The word "decide" comes from the Latin decidere, meaning "to cut off"; being the prefix de plus the root caedere, "to cut". By definition, any decision that is made cuts off other decisions that could have been made. If one makes a right turn at an intersection, she or he precludes the possibility of having made a left turn. And so forth.

Since the work of the Austrian economist Friedrich von Wieser, opportunity cost has been seen as the foundation of the marginal theory of value.

The supply and demand model describes how prices vary as a result of a balance between product availability at each price (supply) and the desires of those with purchasing power at each price (demand). The graph depicts an increase in demand from D₁ to D₂ along with the consequent increase in price and quantity required to reach a new market-clearing equilibrium point on the supply curve (S).

Taxonomy of Microeconomics

Fundamental concepts in microeconomics

Elasticity - Consumer surplus - Producer surplus - Aggregation of individual demand to total, or market, demand

Consumer theory

Preference - Indifference curve - Utility - Marginal utility - Income

Production and pricing theory

Production theory basics - X-efficiency - Factors of production - Production possibility frontier - Production function - Economies of scale - Economies of scope - Profit maximization - Price discrimination - Transfer pricing - Joint product pricing - Price points

Welfare economics

Welfare economics - Pareto efficiency - Kaldor-Hicks efficiency - Edgeworth box - Social welfare function - Income inequality metrics - Lorenz curve - Gini coefficient - Poverty level - Dead weight loss

Industrial organization

Market form - Perfect competition - Monopoly - Monopolistic competition - Oligopoly - Concentration ratio - Herfindahl index

Market failure

- Collective action - Information asymmetry - Externality - Social cost - Free goods - Taxes - Tragedy of the commons - Tragedy of the anticommons - Coase's Penguin

Financial economics

Efficient markets theory - Financial economics - Finance - Risk

International trade

International trade - Terms of trade - Tariff - List of international trade topics

Methodology

General equilibrium - Game theory - Institutional economics - Neoclassical economics - Austrian economics

External Links

• Reffonomics - an online economics textbook covering both Macroeconomics and Microeconomics, Written by Steven M. Reff
• AmosWEB GLOSS*arama - online economics dictionary
• Investopedia - online economics dictionary with investment tips and advice