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Purchasing power parity (PPP) is the measurement of prices in different countries that uses the prices of specific goods to compare the absolute
purchasing power Purchasing power is the amount of goods and services that can be purchased with a unit of currency. For example, if one had taken one unit of currency to a store in the 1950s, it would have been possible to buy a greater number of items than woul ...
of the countries'
currencies A currency, "in circulation", from la, currens, -entis, literally meaning "running" or "traversing" is a standardization of money in any form, in use or circulation as a medium of exchange, for example banknotes and coins. A more general def ...
. PPP is effectively the ratio of the price of a basket of goods at one location divided by the price of the basket of goods at a different location. The PPP inflation and exchange rate may differ from the market exchange rate because of tariffs, and other
transaction cost In economics and related disciplines, a transaction cost is a cost in making any economic trade when participating in a market. Oliver E. Williamson defines transaction costs as the costs of running an economic system of companies, and unlike p ...
s. The Purchasing Power Parity indicator can be used to compare economies regarding their Gross Domestic Product, labour productivity and actual individual consumption, and in some cases to analyse price convergence and to compare the cost of living between places. The calculation of the PPP, according to the OECD, is made through a ''basket of goods'' that contains a "final product list
hat A hat is a head covering which is worn for various reasons, including protection against weather conditions, ceremonial reasons such as university graduation, religious reasons, safety, or as a fashion accessory. Hats which incorporate mecha ...
covers around 3,000 consumer goods and services, 30 occupations in government, 200 types of equipment goods and about 15 construction projects".

# Concept

economic An economy is an area of the production, distribution and trade, as well as consumption of goods and services. In general, it is defined as a social domain that emphasize the practices, discourses, and material expressions associated with ...
term for measuring prices at different locations. It is based on the
law of one price The law of one price (LOOP) states that in the absence of trade frictions (such as transport costs and tariffs), and under conditions of free competition and price flexibility (where no individual sellers or buyers have power to manipulate prices ...
, which says that, if there are no
transaction cost In economics and related disciplines, a transaction cost is a cost in making any economic trade when participating in a market. Oliver E. Williamson defines transaction costs as the costs of running an economic system of companies, and unlike p ...
s nor
trade barrier Trade barriers are government-induced restrictions on international trade. According to the theory of comparative advantage, trade barriers are detrimental to the world economy and decrease overall economic efficiency. Most trade barriers work ...
s for a particular good, then the price for that good should be the same at every location. Ideally, a computer in New York and in Hong Kong should have the same price. If its price is 500 US dollars in New York and the same computer costs 2,000 HK dollars in Hong Kong, PPP theory says the exchange rate should be 4 HK dollars for every 1 US dollar. Poverty, tariffs, transportation and other frictions prevent trading and purchasing of various goods, so measuring a single good can cause a large error. The PPP term accounts for this by using a basket of goods, that is, many goods with different quantities. PPP then computes an inflation and exchange rate as the ratio of the price of the basket in one location to the price of the basket in the other location. For example, if a basket consisting of 1 computer, 1 ton of rice, and half a ton of steel was 1000 US dollars in New York and the same goods cost 6000 HK dollars in Hong Kong, the PPP exchange rate would be 6 HK dollars for every 1 US dollar. The name ''purchasing power parity'' comes from the idea that, with the right exchange rate, consumers in every location will have the same
purchasing power Purchasing power is the amount of goods and services that can be purchased with a unit of currency. For example, if one had taken one unit of currency to a store in the 1950s, it would have been possible to buy a greater number of items than woul ...
. The value of the PPP exchange rate is very dependent on the basket of goods chosen. In general, goods are chosen that might closely obey the law of one price. So, ones traded easily and are commonly available in both locations. Organizations that compute PPP exchange rates use different baskets of goods and can come up with different values. The PPP exchange rate may not match the market exchange rate. The market rate is more volatile because it reacts to changes in demand at each location. Also, tariffs and differences in the price of labour (see Balassa–Samuelson theorem) can contribute to longer-term differences between the two rates. One use of PPP is to predict longer-term exchange rates. Because PPP exchange rates are more stable and are less affected by tariffs, they are used for many international comparisons, such as comparing countries' GDPs or other national income statistics. These numbers often come with the label ''PPP-adjusted''. There can be marked differences between purchasing power adjusted incomes and those converted via market exchange rates. A well-known purchasing power adjustment is the

## Exchange rate prediction

PPP exchange rates are never valued because market exchange rates tend to move in their general direction, over a period of years. There is some value to knowing in which direction the exchange rate is more likely to shift over the long run. In neoclassical
economic theory Economics () is the social science that studies the production, distribution, and consumption of goods and services. Economics focuses on the behaviour and interactions of economic agents and how economies work. Microeconomics anal ...
, the ''purchasing power parity theory'' assumes that the exchange rate between two currencies actually observed in the
foreign exchange market The foreign exchange market (Forex, FX, or currency market) is a global decentralized or over-the-counter (OTC) market for the trading of currencies. This market determines foreign exchange rates for every currency. It includes all as ...
is the one that is used in the purchasing power parity comparisons, so that the same amount of goods could actually be purchased in either currency with the same beginning amount of funds. Depending on the particular theory, purchasing power parity is assumed to hold either in the long run or, more strongly, in the short run. Theories that invoke purchasing power parity assume that in some circumstances a fall in either currency's purchasing power (a rise in its price level) would lead to a proportional decrease in that currency's valuation on the foreign exchange market.

## Identifying manipulation

PPP exchange rates are especially useful when official exchange rates are artificially manipulated by governments. Countries with strong government control of the economy sometimes enforce official exchange rates that make their own currency artificially strong. By contrast, the currency's black market exchange rate is artificially weak. In such cases, a PPP exchange rate is likely the most realistic basis for economic comparison. Similarly, when exchange rates deviate significantly from their long term equilibrium due to speculative attacks or carry trade, a PPP exchange rate offers a better alternative for comparison. In 2011, the
Big Mac Index The Big Mac Index is a price index published since 1986 by ''The Economist'' as an informal way of measuring the purchasing power parity (PPP) between two currencies and providing a test of the extent to which market exchange rates result ...
was used to identify manipulation of inflation numbers by Argentina.

# Issues

The PPP exchange-rate calculation is controversial because of the difficulties of finding comparable baskets of goods to compare purchasing power across countries. Estimation of purchasing power parity is complicated by the fact that countries do not simply differ in a uniform price level; rather, the difference in
food prices Food prices refer to the average price level for food across countries, regions and on a global scale. Food prices have an impact on producers and consumers of food. Price levels depend on the food production process, including food marketing ...
may be greater than the difference in housing prices, while also less than the difference in entertainment prices. People in different countries typically consume different baskets of goods. It is necessary to compare the cost of baskets of goods and services using a price index. This is a difficult task because purchasing patterns and even the goods available to purchase differ across countries. Thus, it is necessary to make adjustments for differences in the quality of goods and services. Furthermore, the basket of goods representative of one economy will vary from that of another: Americans eat more bread; Chinese more rice. Hence a PPP calculated using the US consumption as a base will differ from that calculated using China as a base. Additional statistical difficulties arise with multilateral comparisons when (as is usually the case) more than two countries are to be compared. Various ways of averaging bilateral PPPs can provide a more stable multilateral comparison, but at the cost of distorting bilateral ones. These are all general issues of indexing; as with other price indices there is no way to reduce complexity to a single number that is equally satisfying for all purposes. Nevertheless, PPPs are typically robust in the face of the many problems that arise in using market exchange rates to make comparisons. For example, in 2005 the price of a gallon of gasoline in Saudi Arabia was US$0.91, and in Norway the price was US$6.27. The significant differences in price would not contribute to accuracy in a PPP analysis, despite all of the variables that contribute to the significant differences in price. More comparisons have to be made and used as variables in the overall formulation of the PPP. When PPP comparisons are to be made over some interval of time, proper account needs to be made of
inflation In economics, inflation is an increase in the general price level of goods and services in an economy. When the general price level rises, each unit of currency buys fewer goods and services; consequently, inflation corresponds to a reductio ...
ary effects. In addition to methodological issues presented by the selection of a basket of goods, PPP estimates can also vary based on the statistical capacity of participating countries. The International Comparison Program, which PPP estimates are based on, require the disaggregation of national accounts into production, expenditure or (in some cases) income, and not all participating countries routinely disaggregate their data into such categories. Some aspects of PPP comparison are theoretically impossible or unclear. For example, there is no basis for comparison between the Ethiopian labourer who lives on
teff ''Eragrostis tef'', also known as teff, Williams lovegrass or annual bunch grass, is an annual grass, a species of lovegrass native to the Horn of Africa, notably to both Eritrea and Ethiopia. It is cultivated for its edible seeds, also known a ...
with the Thai labourer who lives on
rice Rice is the seed of the grass species '' Oryza sativa'' (Asian rice) or less commonly '' Oryza glaberrima'' (African rice). The name wild rice is usually used for species of the genera '' Zizania'' and '' Porteresia'', both wild and domesti ...
, because teff is not commercially available in Thailand and rice is not in Ethiopia, so the price of rice in Ethiopia or teff in Thailand cannot be determined. As a general rule, the more similar the price structure between countries, the more valid the PPP comparison. PPP levels will also vary based on the formula used to calculate price matrices. Possible formulas include GEKS-Fisher, Geary-Khamis, IDB, and the superlative method. Each has advantages and disadvantages. Linking regions presents another methodological difficulty. In the 2005 ICP round, regions were compared by using a list of some 1,000 identical items for which a price could be found for 18 countries, selected so that at least two countries would be in each region. While this was superior to earlier "bridging" methods, which do not fully take into account differing quality between goods, it may serve to overstate the PPP basis of poorer countries, because the price indexing on which PPP is based will assign to poorer countries the greater weight of goods consumed in greater shares in richer countries. There are a number of reasons that different measures do not perfectly reflect
standard of living Standard of living is the level of income, comforts and services available, generally applied to a society or location, rather than to an individual. Standard of living is relevant because it is considered to contribute to an individual's quality ...
.

## Range and quality of goods

The goods that the currency has the "power" to purchase are a basket of goods of different types: # Local, non-tradable goods and services (like electric power) that are produced and sold domestically. # Tradable goods such as non-perishable
commodities In economics, a commodity is an economic good, usually a resource, that has full or substantial fungibility: that is, the market treats instances of the good as equivalent or nearly so with no regard to who produced them. The price of a co ...
that can be sold on the international market (like
diamond Diamond is a solid form of the element carbon with its atoms arranged in a crystal structure called diamond cubic. Another solid form of carbon known as graphite is the chemically stable form of carbon at room temperature and pressure ...
s). The more that a product falls into category 1, the further its price will be from the currency
exchange rate In finance, an exchange rate is the rate at which one currency will be exchanged for another currency. Currencies are most commonly national currencies, but may be sub-national as in the case of Hong Kong or supra-national as in the case of ...
, moving towards the PPP exchange rate. Conversely, category 2 products tend to trade close to the currency exchange rate. (See also Penn effect). More processed and expensive products are likely to be
tradable Tradability is the property of a good or service that can be sold in another location distant from where it was produced. A good that is not tradable is called non-tradable. Different goods have differing levels of tradability: the higher the co ...
, falling into the second category, and drifting from the PPP exchange rate to the currency exchange rate. Even if the PPP "value" of the Ethiopian currency is three times stronger than the currency exchange rate, it won't buy three times as much of internationally traded goods like steel, cars and microchips, but non-traded goods like housing, services ("haircuts"), and domestically produced crops. The relative price differential between tradables and non-tradables from high-income to low-income countries is a consequence of the Balassa–Samuelson effect and gives a big cost advantage to labour-intensive production of tradable goods in low income countries (like
Ethiopia Ethiopia, , om, Itiyoophiyaa, so, Itoobiya, ti, ኢትዮጵያ, Ítiyop'iya, aa, Itiyoppiya officially the Federal Democratic Republic of Ethiopia, is a landlocked country in the Horn of Africa. It shares borders with Eritrea to the ...
), as against high income countries (like
Switzerland ). Swiss law does not designate a ''capital'' as such, but the federal parliament and government are in Bern, while other federal institutions, such as the federal courts, are in other cities (Bellinzona, Lausanne, Luzern, Neuchâtel, St. Gall ...
). The corporate cost advantage is nothing more sophisticated than access to cheaper workers, but because the pay of those workers goes farther in low-income countries than high, the relative pay differentials (inter-country) can be sustained for longer than would be the case otherwise. (This is another way of saying that the wage rate is based on average local productivity and that this is below the per capita productivity that factories selling tradable goods to international markets can achieve.) An equivalent
cost In production, research, retail, and accounting, a cost is the value of money that has been used up to produce something or deliver a service, and hence is not available for use anymore. In business, the cost may be one of acquisition, in whic ...
benefit comes from non-traded goods that can be sourced locally (nearer the PPP-exchange rate than the nominal exchange rate in which receipts are paid). These act as a cheaper
factor of production In economics, factors of production, resources, or inputs are what is used in the production process to produce output—that is, goods and services. The utilized amounts of the various inputs determine the quantity of output according to the re ...
than is available to factories in richer countries. It is difficult by GDP PPP to consider the different quality of goods among the countries. The Bhagwati–Kravis–Lipsey view provides a somewhat different explanation from the Balassa–Samuelson theory. This view states that price levels for nontradables are lower in poorer countries because of differences in endowment of labor and capital, not because of lower levels of productivity. Poor countries have more labor relative to capital, so marginal productivity of labor is greater in rich countries than in poor countries. Nontradables tend to be labor-intensive; therefore, because labor is less expensive in poor countries and is used mostly for nontradables, nontradables are cheaper in poor countries. Wages are high in rich countries, so nontradables are relatively more expensive. PPP calculations tend to overemphasise the primary sectoral contribution, and underemphasise the industrial and service sectoral contributions to the economy of a nation.

## Departures from free competition

Linkages between national price levels are also weakened when trade barriers and imperfectly competitive market structures occur together. Pricing to market occurs when a firm sells the same product for different prices in different markets. This is a reflection of inter-country differences in conditions on both the demand side (''e.g.'', virtually no demand for pork in Islamic states) and the supply side (''e.g.'', whether the existing market for a prospective entrant's product features few suppliers or instead is already near-saturated). According to Krugman and Obstfeld, this occurrence of product differentiation and segmented markets results in violations of the law of one price and absolute PPP. Over time, shifts in market structure and demand will occur, which may invalidate relative PPP.

## Differences in price level measurement

Measurement of price levels differ from country to country. Inflation data from different countries are based on different commodity baskets; therefore, exchange rate changes do not offset official measures of inflation differences. Because it makes predictions about price changes rather than price levels, relative PPP is still a useful concept. However, change in the relative prices of basket components can cause relative PPP to fail tests that are based on official price indexes.

## Global poverty line

The global poverty line is a worldwide count of people who live below an international
poverty line The poverty threshold, poverty limit, poverty line or breadline is the minimum level of income deemed adequate in a particular country. The poverty line is usually calculated by estimating the total cost of one year's worth of necessities for ...
, referred to as the dollar-a-day line. This line represents an average of the national poverty lines of the world's poorest countries, expressed in international dollars. These national poverty lines are converted to international currency and the global line is converted back to local currency using the PPP exchange rates from the ICP. PPP exchange rates include data from the sales of high end non-poverty related items which skews the value of food items and necessary goods which is 70 percent of poor peoples' consumption. Angus Deaton argues that PPP indices need to be reweighted for use in poverty measurement; they need to be redefined to reflect local poverty measures, not global measures, weighing local food items and excluding luxury items that are not prevalent or are not of equal value in all localities.

# History

The idea originated with the School of Salamanca in the 16th century, and was developed in its modern form by Gustav Cassel in 1916, in ''The Present Situation of the Foreign Trade''. While Gustav Cassel's use of PPP concept has been traditionally interpreted as his attempt to formulate a positive theory of exchange rate determination, the policy and theoretical context in which Cassel wrote about exchange rates suggests different interpretation. In the years immediately preceding the end of WWI and following it economists and politicians were involved in discussions on possible ways of restoring the
gold standard A gold standard is a monetary system in which the standard economic unit of account is based on a fixed quantity of gold. The gold standard was the basis for the international monetary system from the 1870s to the early 1920s, and from th ...
, which would automatically restore the system of fixed exchange rates among participating nations. The stability of exchange rates was widely believed to be crucial for restoring the international trade and for its further stable and balanced growth. Nobody then was mentally prepared for the idea that flexible exchange rates determined by market forces do not necessarily cause chaos and instability in the peaceful time (and that is what the abandoning of the gold standard during the war was blamed for). Gustav Cassel was among those who supported the idea of restoring the gold standard, although with some alterations. The question, which Gustav Cassel tried to answer in his works written during that period, was not how exchange rates are determined in the free market, but rather how to determine the appropriate level at which exchange rates were to be fixed during the restoration of the system of fixed exchange rates. His recommendation was to fix exchange rates at the level corresponding to the PPP, as he believed that this would prevent trade imbalances between trading nations. Thus, PPP doctrine proposed by Cassel was not really a positive (descriptive) theory of exchange rate determination (as Cassel was perfectly aware of numerous factors that prevent exchange rates from stabilizing at PPP level if allowed to float), but rather a normative (prescriptive) policy advice, formulated in the context of discussions on returning to the gold standard.

# Examples

## Professional

### OECD comparative price levels

Each month, the
Organisation for Economic Co-operation and Development The Organisation for Economic Co-operation and Development (OECD; french: Organisation de coopération et de développement économiques, ''OCDE'') is an intergovernmental organisation with 38 member countries, founded in 1961 to stimulate ...
(OECD) measures the differences in price levels between its member countries by calculating the ratios of PPPs for private final consumption expenditure to exchange rates. The OECD table below indicates the number of US dollars needed in each of the countries listed to buy the same representative basket of consumer goods and services that would cost US$100 in the United States. According to the table, an American living or travelling in Switzerland on an income denominated in US dollars would find that country to be the most expensive of the group, having to spend 47% more US dollars to maintain a standard of living comparable to the US in terms of consumption. ### =Extrapolating PPP rates = Since global PPP estimates—such as those provided by the ICP—are not calculated annually, but for a single year, PPP exchange rates for years other than the benchmark year need to be extrapolated. One way of doing this is by using the country's GDP deflator In economics, the GDP deflator (implicit price deflator) is a measure of the money price of all new, domestically produced, final goods and services in an economy in a year relative to the real value of them. It can be used as a measure of the val ... . To calculate a country's PPP exchange rate in Geary–Khamis dollars for a particular year, the calculation proceeds in the following manner: $\textrm_=\frac$ Where PPPrateX,i is the PPP exchange rate of country X for year i, PPPrateX,b is the PPP exchange rate of country X for the benchmark year, PPPrateU,b is the PPP exchange rate of the United States The United States of America (U.S.A. or USA), commonly known as the United States (U.S. or US) or America, is a country primarily located in North America. It consists of 50 states, a federal district, five major unincorporated territor ... (US) for the benchmark year (equal to 1), GDPdefX,i is the GDP deflator of country X for year i, GDPdefX,b is the GDP deflator of country X for the benchmark year, GDPdefU,i is the GDP deflator of the US for year i, and GDPdefU,b is the GDP deflator of the US for the benchmark year. ### UBS The bank UBS produces its "Prices and Earnings" report every 3 years. Th 2012 report says, "Our reference basket of goods is based on European consumer habits and includes 122 positions". ## Educational To teach PPP, the basket of goods is often simplified to a single good. ### Big Mac Index The Big Mac Index The Big Mac Index is a price index published since 1986 by ''The Economist'' as an informal way of measuring the purchasing power parity (PPP) between two currencies and providing a test of the extent to which market exchange rates result ... is a simple implementation of PPP where the basket contains a single good: a Big Mac The Big Mac is a hamburger sold by the international fast food restaurant chain McDonald's. It was introduced in the Greater Pittsburgh area in 1967 and across the United States in 1968. It is one of the company's flagship products and sign ... burger from McDonald's McDonald's Corporation is an American multinational fast food chain, founded in 1940 as a restaurant operated by Richard and Maurice McDonald, in San Bernardino, California, United States. They rechristened their business as a hamburger st ... restaurants. The index was created and popularized by '' The Economist ''The Economist'' is a British weekly newspaper printed in demitab format and published digitally. It focuses on current affairs, international business, politics, technology, and culture. Based in London, the newspaper is owned by The Eco ... '' as a way to teach economics and to identify over- and under-valued currencies. The Big Mac has the value of being a relatively standardized consumer product that includes input costs from a wide range of sectors in the local economy, such as agricultural commodities (beef, bread, lettuce, cheese), labor (blue and white collar), advertising, rent and real estate costs, transportation, etc. There are some problems with the Big Mac Index. A Big Mac is perishable and not easily transported. That means the law of one price is not likely to keep prices the same in different locations. McDonald's restaurants are not present in every country, which limits the index's usage. Moreover, Big Macs are not sold at every McDonald's ( noticeably in India), which limits its usage further. In the white paper, "Burgernomics", the authors computed a correlation of 0.73 between the Big Mac Index's prices and prices calculated using the Penn World Tables. This single-good index captures most, but not all, of the effects captured by more professional (and more complex) PPP measurement. ''The Economist'' uses The Big Mac Index to identify overvalued and undervalued currencies. That is, ones where the Big Mac is expensive or cheap, when measured using current exchange rates. The January 2019 article states that a Big Mac costs HK$20.00 in Hong Kong and US$5.58 in the United States. The implied PPP exchange rate is 3.58 HK$ per US$. The difference between this and the actual exchange rate of 7.83 suggests that the Hong Kong dollar is 54.2% undervalued. That is, it is cheaper to convert US dollars into Hong Kong dollars and buy a Big Mac in Hong Kong than it is to buy a Big Mac directly in US dollars. ### KFC Index Similar to the Big Mac Index The Big Mac Index is a price index published since 1986 by ''The Economist'' as an informal way of measuring the purchasing power parity (PPP) between two currencies and providing a test of the extent to which market exchange rates result ... , the KFC Index measures PPP with a basket that contains a single item: a KFC KFC (Kentucky Fried Chicken) is an American fast food restaurant chain headquartered in Louisville, Kentucky, that specializes in fried chicken. It is the world's second-largest restaurant chain (as measured by sales) after McDonald's, with ... Original 12/15 pc. bucket. The Big Mac Index cannot be used for most countries in Africa because most do not have a McDonald's restaurant. Thus, the KFC Index was created by Sagaci Research (a market research Market research is an organized effort to gather information about target markets and customers: know about them, starting with who they are. It is an important component of business strategy and a major factor in maintaining competitiveness. M ... firm focusing solely on Africa) to identify over- and under-valued currencies in Africa. For example, the average price of KFC's Original 12 pc. Bucket in the United States in January 2016 was$20.50; while in Namibia it was only $13.40 at market exchange rates. Therefore, the index states the Namibian dollar was undervalued by 33% at that time. ### Nespresso Index Like the Big Mac Index The Big Mac Index is a price index published since 1986 by ''The Economist'' as an informal way of measuring the purchasing power parity (PPP) between two currencies and providing a test of the extent to which market exchange rates result ... , the Nespresso Nestlé Nespresso S.A., trading as Nespresso, is an operating unit of the Nestlé Group, based in Lausanne, Switzerland. Nespresso machines brew espresso and coffee from coffee capsules (or ''pods'' in machines for home or professional use) ... Index measures PPP with a basket that contains a single product: An Arpeggio flavored coffee pod produced and retailed by the Nestlé Group. Its advantage compared to the Big Mac Index is that Nespresso capsules are sold in higher numbers compared to a single Big Mac hamburger. For example, 1 basic Nespresso Capsule costs 0.5 CHF in Switzerland and 0.7 USD The United States dollar (symbol:$; code: USD; also abbreviated US\$ or U.S. Dollar, to distinguish it from other dollar-denominated currencies; referred to as the dollar, U.S. dollar, American dollar, or colloquially buck) is the official ...
in United States. The implied exchange rate is 0.71. The difference between this and the actual exchange rate, 0.93 as of Mid November 2021, suggests the CHF is -22.8% undervalued to the USD.

Like the
Big Mac Index The Big Mac Index is a price index published since 1986 by ''The Economist'' as an informal way of measuring the purchasing power parity (PPP) between two currencies and providing a test of the extent to which market exchange rates result ...
, the iPad index (elaborated by CommSec) compares an item's price in various locations. Unlike the
Big Mac The Big Mac is a hamburger sold by the international fast food restaurant chain McDonald's. It was introduced in the Greater Pittsburgh area in 1967 and across the United States in 1968. It is one of the company's flagship products and sign ...
, however, each iPad is produced in the same place (except for the model sold in Brazil) and all iPads (within the same model) have identical performance characteristics. Price differences are therefore a function of transportation costs, taxes, and the prices that may be realized in individual markets. In 2013, an iPad cost about twice as much in Argentina as in the United States.

# PPP vs. CPI

Consumer price index (CPI) and purchasing power parity (PPP) conversion factors share conceptual similarities. The CPI measures differences in levels of prices of goods and services over time within a country, whereas PPPs measure the change in levels of prices across regions within a country.

*
List of countries by GDP (PPP) GDP (PPP) means gross domestic product based on purchasing power parity. This article includes a list of countries by their forecast estimated GDP (PPP). Countries are sorted by GDP (PPP) forecast estimates from financial and statistical ...
*
List of countries by GDP (PPP) per capita A country's gross domestic product (GDP) at purchasing power parity (PPP) per capita is the PPP value of all final goods and services produced within an economy in a given year, divided by the average (or mid-year) population for the same ...
*
List of IMF ranked countries by GDP This is an alphabetical list of countries by GDP published by IMF. This list includes GDP (nominal), GDP (nominal) per capita, GDP (PPP), GDP (PPP) per capita, Population, and PPP. Circa 2016 Old GDP published by IMF; Irmak Çakıroğlu 201 ...
, Includes IMF ranked PPP of 186 countries * Measures of national income and output * Relative purchasing power parity

# References

Penn World Table

from OECD data * ttp://fx.sauder.ubc.ca/PPP.html Explanations from the U. of British Columbia(also provides daily updated PPP charts)
Purchasing power parities as example of international statistical cooperation
from Eurostat – Statistics Explained
World Bank International Comparison Project
provides PPP estimates for a large number of countries
UBS's "Prices and Earnings" Report 2006
Good report on purchasing power containing a Big Mac index as well as for staples such as bread and rice for 71 world cities.
"Understanding PPPs and PPP based national accounts"
provides an overview of methodological issues in calculating PPP and in designing the ICP under which the main PPP tables (Maddison, Penn World Tables, and World Bank WDI) are based.
List of Countries by Purchasing Power Parity
since 1990 (
World Bank The World Bank is an international financial institution that provides loans and grants to the governments of low- and middle-income countries for the purpose of pursuing capital projects. The World Bank is the collective name for the Int ...
) * The Big Mac Index * Purchasing power parit
Definition, Unesco