Relative price

A relative price is the price of a commodity such as a good or service in terms of another; i.e., the ratio of two prices. A relative price may be expressed in terms of a ratio between the prices of any two goods or the ratio between the price of one good and the price of a market basket of goods (a weighted average of the prices of all other goods available in the market). A relative price is an opportunity cost. Microeconomics can be seen as the study of how economic agents react to changes in relative prices, and of how relative prices are affected by the behavior of those agents.

In a demand equation

In the demand equation Q = f(P) (in which Q is the number of units of a good or service demanded), P is the relative price of the good or service rather than the nominal price. It is the change in a relative price that prompts a change in the quantity demanded. For example, if all prices rise by 10% there is no change in any relative prices, so if consumers' nominal income and wealth also go up by 10% leaving real income and real wealth unchanged, then demand for each good or service will be unaffected. But if the price of a particular good goes up by, say, 2% while the prices of the other goods and services go down enough that the overall price level is unchanged, then the relative price of the particular good has increased while purchasing power has been unaffected, so the quantity of the good demanded will go down.

Budget constraint and indifference curves

Example of a substitution effect

Example of a substitution effect

In the graphical rendition of the theory of consumer choice, as shown in the accompanying graph, the consumer’s choice of the optimal quantities to demand of two goods is the point of tangency between an indifference curve (curved) and the budget constraint (a straight line). The graph shows an initial budget constraint BC1 with resulting choice at tangency point A, and a new budget constraint after a decrease in the absolute price of Y (the good whose quantity is shown horizontally), with resulting choice at tangency point C. In each case the absolute value of the slope of the budget constraint is the ratio of the price of good Y to the price of good X – that is, the relative price of good Y in terms of X.

Distinguishing relative and general price changes

Often inflation makes it difficult for economic agents to immediately distinguish increases in the price of a good which are due to relative price changes from changes in the price which are due to inflation of prices in general. This situation can lead to allocative inefficiency, and is one of the negative effects of inflation.

See also

Relative Prices of commonly valued items what is value?
Value or Price

External links

Aggregation problem

An aggregate in economics is a summary measure describing a market or economy. The aggregation problem is the difficult problem of finding a valid way to treat an empirical or theoretical aggregate as if it reacted like a less-aggregated measure, say, about behavior of an individual agent as described in general microeconomic theory. Examples of aggregates in micro- and macroeconomics relative to less aggregated counterparts are:

Food vs. apples

Price level and real GDP vs. the price and quantity of apples

Capital stock vs. the value of computers of a certain type and the value of steam shovels

Money supply vs. paper currency

General unemployment rate vs. the unemployment rate of civil engineersStandard theory uses simple assumptions to derive general, and commonly accepted, results such as the law of demand to explain market behavior. An example is the abstraction of a composite good. It considers the price of one good changing proportionately to the composite good, that is, all other goods. If this assumption is violated and the agents are subject to aggregated utility functions, restrictions on the latter are necessary to yield the law of demand. The aggregation problem emphasizes:

How broad such restrictions are in microeconomics

Use of broad factor inputs ("labor" and "capital"), real "output", and "investment", as if there was only a single such aggregate is without a solid foundation for rigorously deriving analytical results.Franklin Fisher notes that this has not dissuaded macroeconomists from continuing to use such concepts.

Alchian–Allen effect

The Alchian–Allen effect was described in 1964 by Armen Alchian and William R Allen in the book University Economics (now called Exchange and Production ). It states that when the prices of two substitute goods, such as high and low grades of the same product, are both increased by a fixed per-unit amount such as a transportation cost or a lump-sum tax, consumption will shift toward the higher-grade product. This is true because the added per-unit amount decreases the relative price of the higher-grade product.

Suppose, for example, that high-grade coffee beans are $3/pound and low-grade beans $1.50/pound; in this example, high-grade beans cost twice as much as low-grade beans. Now add a per-pound international shipping cost of $1. The effective prices are now $4 and $2.50; high-grade beans now cost only 1.6 times as much as low-grade beans. This reduced ratio of difference will induce distant coffee-buyers to now choose a higher ratio of high-to-low grade beans than local coffee-buyers.

The effect has been studied as it applies to illegal drugs and it has been shown that the potency of marijuana increased in response to higher enforcement budgets, and there was a similar effect for alcohol in the U.S. during Prohibition. This effect is called Iron law of prohibition or Cardinal rule of prohibition.

Another example is that Australians drink higher-quality Californian wine than Californians, and vice versa, because it is only worth the transportation costs for the most expensive wine.Colloquially, the Alchian–Allen theorem is also known as the “shipping the good apples out” theorem (Thomas Borcherding), or as the “third law of demand.”

Bond valuation

Bond valuation is the determination of the fair price of a bond. As with any security or capital investment, the theoretical fair value of a bond is the present value of the stream of cash flows it is expected to generate. Hence, the value of a bond is obtained by discounting the bond's expected cash flows to the present using an appropriate discount rate. In practice, this discount rate is often determined by reference to similar instruments, provided that such instruments exist. Various related yield-measures are then calculated for the given price.

If the bond includes embedded options, the valuation is more difficult and combines option pricing with discounting. Depending on the type of option, the option price as calculated is either added to or subtracted from the price of the "straight" portion. See further under Bond option. This total is then the value of the bond.


CAN SLIM refers to the acronym developed by the American stock research and education company Investor's Business Daily (IBD). IBD claims CANSLIM represents the seven characteristics that top-performing stocks often share before making their biggest price gains. It was developed in the 1950s by Investor's Business Daily founder William O'Neil. The method was named the top-performing investment strategy from 1998-2009 by the American Association of Individual Investors. In 2015, an exchange-traded fund (ETF) was launched focusing on the companies listed on the IBD 50, a computer generated list published by Investors Business Daily that highlights stocks based on the CAN SLIM investment criteria.

Cable-stayed bridge

A cable-stayed bridge has one or more towers (or pylons), from which cables support the bridge deck. A distinctive feature are the cables or stays, which run directly from the tower to the deck, normally forming a fan-like pattern or a series of parallel lines. This is in contrast to the modern suspension bridge, where the cables supporting the deck are suspended vertically from the main cable, anchored at both ends of the bridge and running between the towers. The cable-stayed bridge is optimal for spans longer than cantilever bridges and shorter than suspension bridges. This is the range within which cantilever bridges would rapidly grow heavier, and suspension bridge cabling would be more costly.

Cable-stayed bridges have been known since the 16th century and used widely since the 19th. Early examples often combined features from both the cable-stayed and suspension designs, including the Brooklyn Bridge. The design fell from favor through the 20th century as larger gaps were bridged using pure suspension designs, and shorter ones using various systems built of reinforced concrete. It once again rose to prominence in the later 20th century when the combination of new materials, larger construction machinery, and the need to replace older bridges all lowered the relative price of these designs.

Comparative advantage

The law or principle of comparative advantage holds that under free trade, an agent will produce more of and consume less of a good for which they have a comparative advantage. Comparative advantage is the economic reality describing the work gains from trade for individuals, firms, or nations, which arise from differences in their factor endowments or technological progress. In an economic model, agents have a comparative advantage over others in producing a particular good if they can produce that good at a lower relative opportunity cost or autarky price, i.e. at a lower relative marginal cost prior to trade. One does not compare the monetary costs of production or even the resource costs (labor needed per unit of output) of production. Instead, one must compare the opportunity costs of producing goods across countries.David Ricardo developed the classical theory of comparative advantage in 1817 to explain why countries engage in international trade even when one country's workers are more efficient at producing every single good than workers in other countries. He demonstrated that if two countries capable of producing two commodities engage in the free market, then each country will increase its overall consumption by exporting the good for which it has a comparative advantage while importing the other good, provided that there exist differences in labor productivity between both countries. Widely regarded as one of the most powerful yet counter-intuitive insights in economics, Ricardo's theory implies that comparative advantage rather than absolute advantage is responsible for much of international trade.

Elasticity of substitution

Elasticity of substitution is the elasticity of the ratio of two inputs to a production (or utility) function with respect to the ratio of their marginal products (or utilities). In a competitive market, it measures the percentage change in the ratio of two inputs used in response to a percentage change in their prices. It measures the curvature of an isoquant and thus, the substitutability between inputs (or goods), i.e. how easy it is to substitute one input (or good) for the other.


Income is the consumption and saving opportunity gained by an entity within a specified timeframe, which is generally expressed in monetary terms. For households and individuals, "income is the sum of all the wages, salaries, profits, interest payments, rents, and other forms of earnings received in a given period of time."In the field of public economics, the concept may comprise the accumulation of both monetary and non-monetary consumption ability, with the former (monetary) being used as a proxy for total income.

For a firm, gross income can be defined as sum of all revenue. Net income nets out expenses: net income equals revenue minus expenses.

Increase in incomeIncome per capita has been increasing steadily in almost every country. Many factors contribute to people having a higher income, including education, globalisation and favorable political circumstances such as economic freedom and peace. Increases in income also tend to lead to people choosing to work fewer hours.

Developed countries (defined as countries with a "developed economy") have higher incomes as opposed to developing countries tending to have lower incomes.

Karl Brunner (economist)

Karl Brunner (; German: [ˈbrʊnər]; 16 February 1916 – 9 May 1989) was a Swiss economist.


In Austrian business cycle theory, malinvestments are badly allocated business investments, due to artificially low cost of credit and an unsustainable increase in money supply. Central banks are often blamed for causing malinvestments, such as the dot-com bubble and the United States housing bubble. Austrian economists such as Nobel laureate F. A. Hayek advocate the idea that malinvestment occurs due to the combination of fractional reserve banking and artificially low interest rates misleading relative price signals which eventually necessitate a corrective contraction—a boom followed by a bust.The concept dates back to at least 1867. In 1940, Ludwig von Mises wrote, "The popularity of inflation and credit expansion, the ultimate source of the repeated attempts to render people prosperous by credit expansion, and thus the cause of the cyclical fluctuations of business, manifests itself clearly in the customary terminology. The boom is called good business, prosperity, and upswing. Its unavoidable aftermath, the readjustment of conditions to the real data of the market, is called crisis, slump, bad business, depression. People rebel against the insight that the disturbing element is to be seen in the malinvestment and the overconsumption of the boom period and that such an artificially induced boom is doomed. They are looking for the philosophers' stone to make it last."


The numéraire (or numeraire) is a basic standard by which value is computed. In mathematical economics it is a tradeable economic entity in terms of whose price the relative prices of all other tradeables are expressed. In a monetary economy, acting as the numéraire is one of the functions of money, to serve as a unit of account: to provide a common benchmark relative to which the worths of various goods and services are measured. Using a numeraire, whether monetary or some consumable good, facilitates value comparisons when only the relative prices are relevant, as in general equilibrium theory. When economic analysis refers to a particular good as the numéraire, one says that all other prices are normalized by the price of that good. For example, if a unit of good g has twice the market value of a unit of the numeraire, then the (relative) price of g is 2. Since the value of one unit of the numeraire relative to one unit of itself is 1, the price of the numeraire is always 1.

Penn World Table

The Penn World Table (PWT) is a set of national-accounts data developed and maintained by scholars at the University of California, Davis and the Groningen Growth Development Centre of the University of Groningen to measure real GDP across countries and over time. Successive updates have added countries (currently 167), years (1950-2014), and data on capital, productivity, employment and population. The current version of the database, version 9, thus allows for comparisons of relative GDP per capita, as a measure of standard of living, the productive capacity of economies and their productivity level. Compared to other databases, such as the World Bank's World Development Indicators, the time period covered is larger and there is more data that is useful for comparing productivity across countries and over time.

A common practice for comparing GDPs across countries has been to use exchange rates. However, this assumes that this relative price - based on traded products - is representative of all relatives prices in the economy, i.e. that it represents the purchasing power parity (PPP) of each currency. By contrast, PWT uses detailed prices within each country for different expenditure categories, regardless of whether the output is traded internationally (say, computers) or not (say, haircuts). These detailed prices are combined into an overall relative price level, typically referred to as the country's PPP. The detailed prices used to compute PPPs are based on data published by the World Bank as part of the International Comparison Program (ICP).

An empirical finding documented extensively by PWT is the Penn effect, the finding that real GDP is substantially understated when using exchange rates instead of PPPs in comparing GDP across countries. The most common argument to explain this finding is the Balassa-Samuelson effect, which argues that as countries grow richer, productivity increases mostly in manufacturing and other traded activities. This drives up wages and thus prices of many (non-traded) services, increasing the overall price level of the economy. The result is that poorer countries, such as China, are shown to be much richer based on PPP-converted real GDP than based on exchange-rate-converted GDP.

The database gets its name from the original developers at the University of Pennsylvania, Robert Summers, Irving Kravis and Alan Heston.

Price premium

Price premium, or relative price, is the percentage by which a product's selling price exceeds (or falls short of) a benchmark price. Marketers need to monitor price premiums as early indicators of competitive pricing strategies. Changes in price premiums can also be signs of product shortages, excess inventories, or other changes in the relationships between supply and demand. In a survey of nearly 200 senior marketing managers, 54 percent responded that they found the "price premium" metric very useful.

Relative value (economics)

In finance, relative value is the attractiveness measured in terms of risk, liquidity, and return of one financial instrument relative to another, or for a given instrument, of one maturity relative to another. The concept arises in economics, business and investment.

Relevant market

In competition law, a relevant market is a market in which a particular product or service is sold. It is the intersection of a relevant product market and a relevant geographic market. The European Commission defines a relevant market and its product and geographic components as follows:

A relevant product market comprises all those products and/or services which are regarded as interchangeable or substitutable by the consumer by reason of the products' characteristics, their prices and their intended use;

A relevant geographic market comprises the area in which the firms concerned are involved in the supply of products or services and in which the conditions of competition are sufficiently homogeneous.

Stolper–Samuelson theorem

The Stolper–Samuelson theorem is a basic theorem in Heckscher–Ohlin trade theory. It describes the relationship between relative prices of output and relative factor rewards—specifically, real wages and real returns to capital.

The theorem states that—under specific economic assumptions (constant returns to scale, perfect competition, equality of the number of factors to the number of products)—a rise in the relative price of a good will lead to a rise in the return to that factor which is used most intensively in the production of the good, and conversely, to a fall in the return to the other factor.

Substitution effect

In economics and particularly in consumer choice theory, the substitution effect is one component of the effect of a change in the price of a good upon the amount of that good demanded by a consumer, the other being the income effect.

When a good's price decreases, if hypothetically the same consumption bundle were to be retained, income would be freed up which could be spent on a combination of more of each of the goods. Thus the new total consumption bundle chosen, compared to the old one, reflects both the effect of the changed relative prices of the two goods (one unit of one good can now be traded for a different quantity of the other good than before as the ratio of their prices has changed) and the effect of the freed-up income. The effect of the relative price change is called the substitution effect, while the effect due to income having been freed up is called the income effect.

If income is altered in response to the price change such that a new budget line is drawn passing through the old consumption bundle but with the slope determined by the new prices and the consumer's optimal choice is on this budget line, the resulting change in consumption is called the Slutsky substitution effect. The idea is that the consumer is given enough money to purchase her old bundle at the new prices, and her choice changes are seen.

If instead, a new budget line is found with the slope determined by the new prices but tangent to the indifference curve going through the old bundle, the difference between the new point of tangency and the old bundle is the Hicks substitution effect. The idea now is that the consumer is given just enough income to achieve her old utility at the new prices, and how her choice changes is seen. The Hicks substitution effect is illustrated in the next section.

Some authors refer to one of these two concepts as simply the substitution effect. The popular textbook by Varian describes the Slutsky variant as the primary one, but also gives a good explanation of the distinction.

The same concepts also apply if the price of one good goes up instead of down, with the substitution effect reflecting the change in relative prices and the income effect reflecting the fact the income has been soaked up into additional spending on the retained units of the now-pricier good.

For example, if the price of a given commodity (say Pepsi) falls, with no change in the price of its substitute (say Coca-Cola), then Pepsi will become relatively cheaper and will be substituted for Coca-Cola; thus the demand for Pepsi will rise.

Terms of trade

The terms of trade (TOT) is the relative price of imports in terms of exports and is defined as the ratio of export prices to import prices. It can be interpreted as the amount of import goods an economy can purchase per unit of export goods.

An improvement of a nation's terms of trade benefits that country in the sense that it can buy more imports for any given level of exports. The terms of trade may be influenced by the exchange rate because a rise in the value of a country's currency lowers the domestic prices of its imports but may not directly affect the prices of the commodities it exports.

Trade-weighted effective exchange rate index

The trade-weighted effective exchange rate index, a common form of the effective exchange rate index, is a multilateral exchange rate index. It is compiled as a weighted average of exchange rates of home versus foreign currencies, with the weight for each foreign country equal to its share in trade. Depending on the purpose for which it is used, it can be export-weighted, import-weighted, or total-external trade weighted.

The trade-weighted effective exchange rate index is an economic indicator for comparing the exchange rate of a country against those of their major trading partners. By design, movements in the currencies of those trading partners with a greater share in an economy's exports and imports will have a greater effect on the effective exchange rate. In a multilateral, highly globalized, world, the effective exchange rate index is much more useful than a bilateral exchange rate, such as that between the Australian dollar and the United States dollar, for assessing changes in the competitiveness due to exchange rate movements.

Generally, the weighting method is geometric weighting rather than arithmetic weighting. Refer to weighted geometric mean.

The use of trade weights in a globalized economy is potentially misleading, because the amount of value added content in exports destined for a country may deviate significantly from the gross value of exports shipped to that country. See the entry under effective exchange rate index for an alternative approach to compiling an effective exchange rate index.

The interpretation of the effective exchange rate is that if the index rises, other things being equal, the purchasing power of that currency also rises (the currency strengthened against those of the country's or area's trading partners). That will reduce the cost of imports but will undermine the competitiveness of exports. Other things refer, in particular, to the relative inflation rates of the economy as compared to the inflation rates of its trading partners. To account for all effects of relative inflation rates, the real effective exchange rate index is compiled as the product of the effective exchange rate index and the relative price index between the home economy and the trading partners.

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