Supply and demand, prices and quantities

The supply and demand model describes how prices vary as a result of a balance between product availability and demand. The graph depicts an increase (that is, right-shift) in demand from D₁ to D₂ along with the consequent increase in price and quantity required to reach a new equilibrium point on the supply curve (S).

The theory of demand and supply is an organizing principle to explain prices and quantities of goods sold and changes thereof in a market economy. In microeconomic theory, it refers to price and output determination in a perfectly competitive market. This has served as a building block for modeling other market structures and for other theoretical approaches.

For a given market of a commodity, demand shows the quantity that all prospective buyers would be prepared to purchase at each unit price of the good. Demand is often represented using a table or a graph relating price and quantity demanded (see boxed figure). Demand theory describes individual consumers as rationally choosing the most preferred quantity of each good, given income, prices, tastes, etc. A term for this is 'constrained utility maximization' (with income as the constraint on demand). Here, utility refers to the (hypothesized) preference relation for individual consumers. Utility and income are then used to model hypothesized properties about the effect of a price change on the quantity demanded. The law of demand states that, in general, price and quantity demanded in a given market are inversely related. In other words, the higher the price of a product, the less of it people would be able and willing to buy of it (other things unchanged). As the price of a commodity rises, overall purchasing power decreases (the income effect) and consumers move toward relatively less expensive goods (the substitution effect). Other factors can also affect demand; for example an increase in income will shift the demand curve outward relative to the origin, as in the figure.

Supply is the relation between the price of a good and the quantity available for sale from suppliers (such as producers) at that price. Supply is often represented using a table or graph relating price and quantity supplied. Producers are hypothesized to be profit-maximizers, meaning that they attempt to produce the amount of goods that will bring them the highest profit. Supply is typically represented as a directly proportional relation between price and quantity supplied (other things unchanged). In other words, the higher the price at which the good can be sold, the more of it producers will supply. The higher price makes it profitable to increase production. At a price below equilibrium, there is a shortage of quantity supplied compared to quantity demanded. This pulls the price up. At a price above equilibrium, there is a surplus of quantity supplied compared to quantity demanded. This pushes the price down. The model of supply and demand predicts that for given supply and demand curves, price and quantity will stabilize at the price that makes quantity supplied equal to quantity demanded. This is at the intersection of the two curves in the graph above, market equilibrium.

For a given quantity of a good, the price point on the demand curve indicates the value, or marginal utility to consumers for that unit of output. It measures what the consumer would be prepared to pay for the corresponding unit of the good. The price point on the supply curve measures marginal cost, the increase in total cost to the supplier for the corresponding unit of the good. The price in equilibrium is determined by supply and demand. In a perfectly competitive market, supply and demand equate cost and value at equilibrium.

Demand and supply can also be used to model the distribution of income to the factors of production, including labour and capital, through factor markets. In a labour market for example, the quantity of labour employed and the price of labour (the wage rate) are modeled as set by the demand for labour (from business firms etc. for production) and supply of labour (from workers).

Demand and supply are used to explain the behavior of perfectly competitive markets, but their usefulness as a standard of performance extends to any type of market. Demand and supply can also be generalized to explain variables applying to the whole economy, for example, quantity of total output and the general price level, studied in macroeconomics.

Diminishing marginal utility, given quantification

In supply-and-demand analysis, the price of a good coordinates production and consumption quantities. Price and quantity have been described as the most directly observable characteristics of a good produced for the market. Supply, demand, and market equilibrium are theoretical constructs linking price and quantity. But tracing the effects of factors predicted to change supply and demand—and through them, price and quantity—is a standard exercise in applied microeconomics and macroeconomics. Economic theory can specify under what circumstances price serves as an efficient communication device to regulate quantity. A real-world application might attempt to measure how much variables that increase supply or demand change price and quantity.

Marginalism is the use of marginal concepts within economics. Marginal concepts are associated with a specific change in the quantity used of a good or of a service, as opposed to some notion of the over-all significance of that class of good or service, or of some total quantity thereof. The central concept of marginalism proper is that of marginal utility, but marginalists following the lead of Alfred Marshall were further heavily dependent upon the concept of marginal physical productivity in their explanation of cost; and the neoclassical tradition that emerged from Britis marginalism generally abandoned the concept of utility and gave marginal rates of substitution a more fundamental rôle in analysis

Market failure

Pollution can be a simple example of market failure. If Cost of production are not borne by producers but are by the environment, accident victims or others, then prices are distorted.

The term "market failure" encompasses several problems which may undermine standard economic assumptions. Although economists categorise market failures differently, the following categories emerge in the main texts.

• Natural monopoly, or the overlapping concepts of "practical" and "technical" monopoly, involves a failure of competition as a restraint on producers. The problem is described as one where the more of a product is made, the greater the returns are. This means it only makes economic sense to have one producer.
• Information asymmetric arise where one party has more or better information than the other. The existence of information asymmetry gives rise to problems such as moral hazard, and adverse selection, studied in contract theory. The economics of information has relevance in many fields, including finance, insurance, contract law, and decision-making under risk and uncertainty.^[29]
• Incomplete markets is a term used for a situation where buyers and sellers do not know enough about each others positions to price goods and services properly. Based on George Akerlof's Market of Lemon article, the paradigm example is of a dodgy second hand car market. Customers without the possibility to know for certain whether they are buying a "lemon" will push the average price down below what a good quality second hand car would be. In this way, prices may not reflect true values.
• Public Goods are goods which are undersupplied in a typical market. The defining features are that people can consume public goods without having to pay for them and that more than one person can consume the good at the same time.
• Externalities occur where there are significant social costs or benefits from production or consumption that are not reflected in market prices. For example, air pollution may generate a negative externality, and education may generate a positive externality (less crime, etc.). Governments often tax and otherwise restrict the sale of goods that have negative externalities and subsidize or otherwise promote the purchase of goods that have positive externalities in an effort to correct the price distortions caused by these externalities. Elementary demand-and-supply theory predicts equilibrium but not the speed of adjustment for changes of equilibrium due to a shift in demand or supply.In many areas, some form of is postulated to account for quantities, rather than prices, adjusting in the short run to changes on the demand side or the supply side. This includes standard analysis of the business cycle in macroeconomics. Analysis often revolves around causes of such price stickiness and their implications for reaching a hypothesized long-run equilibrium. Examples of such price stickiness in particular markets include wage rates in labour markets and posted prices in markets deviating from perfect competition.
• Macroeconomic instability, addressed below, is a prime source of market failure, whereby a general loss of business confidence or external shock can grind production and distribution to a halt, undermining ordinary markets that are otherwise sound.

Some specialised fields of economics deal in market failure more than others. The economics of the public sector is one example, since where markets fail, some kind of regulatory or government programme is the remedy. Much environmental economics concerns externalities or "public bads". Policy options include regulations that reflect cost-benefit analysis or market solutions that change incentives, such as emission fees or redefinition of property rights Environmental economics is related to ecological economics but there are differences.

Most environmental economists have been trained as economists. They apply the tools of economics to address environmental problems, many of which are related to so-called market failures—circumstances wherein the "invisible hand" of economics is unreliable.^[ Most ecological economists have been trained as ecologists, but have expanded the scope of their work to consider the impacts of humans and their economic activity on ecological systems and services, and vice-versa. This field takes as its premise that economics is a strict subfield of ecology. Ecological economics is sometimes described as taking a more pluralistic approach to environmental problems and focuses more explicitly on long-term environmental sustainability and issues of scale. Agricultural economics is one the oldest and most established fields of economics. It is the study of the economic forces that affect the agricultural sector and the agricultural sector's impact on the rest of the economy. It is an area of economics that, thanks to the necessity of applying microeconomic theories to complex real world situations, has given rise to many important advances of more general applicability; the role of risk and uncertainty, the behaviour of households and links between property rights and incentives. More recently policy areas such as international commodity trade and the environment have been stressed.

Firms

One of the assumptions of perfectly competitive markets is that there are many producers, none of whom can influence prices or act independently of market forces. In reality, however, people do not simply trade on markets, they work and produce through firms. The most obvious kinds of firms are corporations, partnerships and trusts. According to Ronald Coase people begin to organise their production in firms when the costs of doing business becomes lower than doing it on the market. Firms combine labour and capital, and can achieve far greater economies of scale (when producing two or more things is cheaper than one thing) than individual market trading.

Labour economics seeks to understand the functioning of the market and dynamics for labour. Labour markets function through the interaction of workers and employers. Labour economics looks at the suppliers of labour services (workers), the demanders of labour services (employers), and attempts to understand the resulting patterns of wages and other labour income and of employment and unemployment, Practical uses include assisting the formulation of full employment of policies

Public sector

Public finance is the field of economics that deals with budgeting the revenues and expenditures of a public sector entity, usually government. The subject addresses such matters as tax incidence (who really pays a particular tax), cost-benefit analysis of government programs, effects on economic efficiency and income distribution of different kinds of spending and taxes, and fiscal politics. The latter, an aspect of public choice theory, models public-sector behavior analogously to microeconomics, involving interactions of self-interested voters, politicians, and bureaucrats.

Much of economics is positive, seeking to describe and predict economic phenomena. Normative economics seeks to identify what is economically good and bad.

Welfare economics is a normative branch of economics that uses microeconomic techniques to simultaneously determine the allocative efficiency within an economy and the income distribution associated with it. It attempts to measure social welfare by examining the economic activities of the individuals that comprise society

Macroeconomics

Circulation in macroeconomics

Macroeconomics examines the economy as a whole to explain broad aggregates and their interactions "top down," that is, using a simplified form of general-equilibrium theory. Such aggregates include national income and output, the unemployment rate, and price inflation and subaggregates like total consumption and investment spending and their components. It also studies effects of monetary policy and fiscal policy. Since at least the 1960s, macroeconomics has been characterized by further integration as to micro-based modeling of sectors, including rationality of players, efficient use of market information, and imperfect competition. This has addressed a long-standing concern about inconsistent developments of the same subject. Macroeconomic analysis also considers factors affecting the long-term level and growth of national income. Such factors include capital accumulation, technological change and labor force growth.

Growth

Growth economics studies factors that explain economic growth – the increase in output per capita of a country over a long period of time. The same factors are used to explain differences in the level of output per capita between countries. Much-studied factors include the rate of investment, population growth, and technological change. These are represented in theoretical and empirical forms (as in the neoclassical growth model) and in growth accounting.

Inflation and monetary policy

A 640 BCE one-third stater electrum coin from Lydia, shown larger. One of the first standardized coins.

Some different currencies. Exchange rates are determined in currency markets used in international trade.

Money is a means of final payment for goods in most price system economies and the unit of account in which prices are typically stated. It includes currency held by the nonbank public and checkable deposits. It has been described as a social convention, like language, useful to one largely because it is useful to others. As a medium of exchange, money facilitates trade. Its economic function can be contrasted with barter (non-monetary exchange). Given a diverse array of produced goods and specialized producers, barter may entail a hard-to-locate double coincidence of wants as to what is exchanged, say apples and a book. Money can reduce the transaction cost of exchange because of its ready acceptability. Then it is less costly for the seller to accept money in exchange, rather than what the buyer produces.

At the level of an economy, theory and evidence are consistent with a positive relationship running from the total money supply to the nominal value of total output and to the general price level. For this reason, management of the money supply is a key aspect of monetary policy

International economics

International trade studies determinants of goods-and-services flows across international boundaries. It also concerns the size and distribution of gains from trade. Policy applications include estimating the effects of changing tariff rates and trade quotas. International finance is a macroeconomic field which examines the flow of capital across international borders, and the effects of these movements on exchange rates. Increased trade in goods, servics and capital between countries is a major effect of contemporary globalization

History of economic thought

The city states of Sumer developed a trade and market economy based originally on the commodity money of the Shekel which was a certain weight measure of barley, while the Babylonians and their city state neighbors later developed the earliest system of economics using a metric of various commodities, that was fixed in a legal code. The early law codes from Sumer could be considered the first (written) economic formula, and had many attributes still in use in the current price system today... such as codified amounts of money for business deals (interest rates), fines in money for 'wrong doing', inheritance rules, laws concerning how private property is to be taxed or divided, etc.^[For a summary of the laws, see Babylonian law and Ancient economic thought.

Economic thought dates from earlier Mesopotamian, Greek, Roman, Indian, Chinese, Persian and Arab civilizations. Notable writers include Aristotle, Chanakya, Qin Shi Huang, Thomas Aquinas and Ibn Khaldun through to the 14th century. Joseph Schumpeter initially considered the late scholastics of the 14th to 17th centuries as "coming nearer than any other group to being the 'founders' of scientific economics" as to monetary, interest, and value theory within a natural-law perspective. After discovering Ibn Khaldun's Muqaddimah, however, Schumpeter later viewed Ibn Khaldun as being the closest forerunner of modern economics, as many of his economic theories were not known in Europe until relatively modern times.

Two other groups, later called 'mercantilists' and 'physiocrats', more directly influenced the subsequent development of the subject. Both groups were associated with the rise of economic nationalism and modern capitalism in Europe. Mercantilism was an economic doctrine that flourished from the 16th to 18th century in a prolific pamphlet literature, whether of merchants or statesmen. It held that a nation's wealth depended on its accumulation of gold and silver. Nations without access to mines could obtain gold and silver from trade only by selling goods abroad and restricting imports other than of gold and silver. The doctrine called for importing cheap raw materials to be used in manufacturing goods, which could be exported, and for state regulation to impose protective tariffs on foreign manufactured goods and prohibit manufacturing in the colonies

International finance

History of economic thought

The city states of Sumer developed a trade and market economy based originally on the commodity money of the Shekel which was a certain weight measure of barley, while the Babylonians and their city state neighbors later developed the earliest system of economics using a metric of various commodities, that was fixed in a legal code. The early law codes from Sumer could be considered the first (written) economic formula, and had many attributes still in use in the current price system today... such as codified amounts of money for business deals (interest rates), fines in money for 'wrong doing', inheritance rules, laws concerning how private property is to be taxed or divided, etc.^[For a summary of the laws, see Babylonian law and Ancient economic thought.

Economic thought dates from earlier Mesopotamian, Greek, Roman, Indian, Chinese, Persian and Arab civilizations. Notable writers include Aristotle, Chanakya, Qin Shi Huang, Thomas Aquinas and Ibn Khaldun through to the 14th century. Joseph Schumpeter initially considered the late scholastics of the 14th to 17th centuries as "coming nearer than any other group to being the 'founders' of scientific economics" as to monetary, interest, and value theory within a natural-law perspective. After discovering Ibn Khaldun's Muqaddimah, however, Schumpeter later viewed Ibn Khaldun as being the closest forerunner of modern economics, as many of his economic theories were not known in Europe until relatively modern times.

Two other groups, later called 'mercantilists' and 'physiocrats', more directly influenced the subsequent development of the subject. Both groups were associated with the rise of economic nationalism and modern capitalism in Europe. Mercantilism was an economic doctrine that flourished from the 16th to 18th century in a prolific pamphlet literature, whether of merchants or statesmen. It held that a nation's wealth depended on its accumulation of gold and silver. Nations without access to mines could obtain gold and silver from trade only by selling goods abroad and restricting imports other than of gold and silver. The doctrine called for importing cheap raw materials to be used in manufacturing goods, which could be exported, and for state regulation to impose protective tariffs on foreign manufactured goods and prohibit manufacturing in the colonies.