Cost of living index


Cost of living index

A cost-of-living index is a theoretical price index that measures relative cost of living over time.

There are many different methodologies that have been developed to approximate cost-of-living indexes, including methods that allow for substitution among items as relative prices change.

A Konüs index is a type of cost-of-living index that uses an expenditure function such as one used in assessing expected compensating variation. The expected indirect utility is equated in both periods.

The United States Consumer Price Index (CPI) is a price index that is based on the idea of a cost-of-living index. The two are related but not exactly interchangeable, however. The US Department of Labor's Bureau of Labor Statistics (BLS) explains the difference:

"The CPI frequently is called a cost-of-living index, but it differs in important ways from a complete cost-of-living measure. BLS has for some time used a cost-of-living framework in making practical decisions about questions that arise in constructing the CPI. A cost-of-living index is a conceptual measurement goal, however, not a straightforward alternative to the CPI. A cost-of-living index would measure changes over time in the amount that consumers need to spend to reach a certain utility level or standard of living. Both the CPI and a cost-of-living index would reflect changes in the prices of goods and services, such as food and clothing that are directly purchased in the marketplace; but a complete cost-of-living index would go beyond this to also take into account changes in other governmental or environmental factors that affect consumers' well-being. It is very difficult to determine the proper treatment of public goods, such as safety and education, and other broad concerns, such as health, water quality, and crime that would constitute a complete cost-of-living framework." [http://www.bls.gov/cpi/cpifaq.htm#Question_4 US Consumer Price Index FAQ question #4]

Economic theory

The basis for the theory behind the cost of living index is attributed to Russian economist A.A. Konüs. [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 313. ] The economic theory behind the cost of living index assumes that consumers are optimizers and get as much utility as possible from the money that they have to spend. These assumptions can be shown to lead to a "consumer's cost function", "C"("u","p"), the cost of achieving utility level "u" given a set of prices "p". [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 314.] Assuming that the cost function holds across time (i.e., people get the same amount of utility from one set of purchases in year as they would have buying the same set in a different year) leads to a "true cost of living index." The general form for Konüs's true cost of living index compares the consumer's cost function given the prices in one year with the consumer's cost function given the prices in a different year:

:P_K(p^0,p^1,u)=frac{C(u,p^1)}{ C(u,p^0)}

Since "u" can be defined as the utility received from a set of goods measured in quantity, "q", "u" can be replaced with "f"("q") to produce a version of the true cost of living index that is based on price and quantities like most other price indices:

:P_K(p^0,p^1,q)=frac{C(f(q),p^1)}{ C(f(q),p^0)} [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 314.]

In simpler terms, the true cost of living index is the cost of achieving a certain level of utility (or standard of living) in one year relative to the cost of achieving the same level the next year.

Utility is not directly measurable, so the true cost of living index only serves as a theoretical ideal, not a practical price index formula. However, more practical formulas can be evaluated based on their relationship to the true cost of living index. One of the most commonly used formulas for consumer price indices, the Laspeyres price index, compares the cost of what a consumer bought in one time period (q0) with how much it would have cost to buy the same set of goods in services in a later period. Since the utility from q0 in the first year should be equal to the utility from q0 in the next year, Laspeyres gives the upper bound for the true cost of living index. [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 314.] Laspeyres only serves as an upper bound, because consumers could turn to substitute goods for those goods that have gotten more expensive and achieved the same level of utility from q0 for a lower cost. In contrast, a Paasche price index uses the cost of a set of goods purchased in one time period with the cost it would have taken to buy the same set of goods in an earlier time period. It can be shown that the Paasche is a lower bound for true cost of living index. [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 315.] Since upper and lower bounds of the true cost of living index can be found, respectively, through the Laspeyres and Paasche indices, the geometric average of the two, known as the Fisher price index, is a close approximation of the true cost of living index if the upper and lower bounds are not too far apart. [ILO CPI manual [http://www.ilo.org/public/english/bureau/stat/download/cpi/ch17.pdf] , 316.]

References


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • cost of living index — ➔ index1 * * * cost of living index UK US noun [C, usually singular] ► ECONOMICS a list of the prices of basic goods and services, showing how they change in a particular period of time, as a way of measuring inflation: »The newspaper s own… …   Financial and business terms

  • cost–of–living index — n: consumer price index Merriam Webster’s Dictionary of Law. Merriam Webster. 1996 …   Law dictionary

  • cost of living index — An official number showing the cost of living at a certain date compared with that at another date taken as a standard • • • Main Entry: ↑cost …   Useful english dictionary

  • Cost-of-living index — A cost of living index is a theoretical price index that measures relative cost of living over time or regions. It is an index that measures differences in the price of goods and services, and allows for substitutions to other items as prices… …   Wikipedia

  • cost-of-living index — /kɒst əv ˈlɪvɪŋ ˌɪndɛks/ (say kost uhv living .indeks) noun an index compiled from official statistics which represents the monthly rise or fall in the cost of living in terms of points as compared with a selected earlier year …   Australian English dictionary

  • cost-of-living index — /ˌkɒst əv lɪvɪŋ ˌɪndeks/ noun the way of measuring the cost of living which is shown as a percentage increase on the figure for the previous year. It is similar to the consumer price index, but includes other items such as the interest on… …   Marketing dictionary in english

  • cost-of-living index — /ˌkɒst əv lɪvɪŋ ˌɪndeks/ noun a way of measuring the cost of living which is shown as a percentage increase on the figure for the previous year. It is similar to the consumer price index, but includes other items such as the interest on mortgages …   Dictionary of banking and finance

  • cost of living index — index which records the average cost of the necessities of life (i.e. food, clothing, shelter) …   English contemporary dictionary

  • cost-of-living index — noun an index of the cost of all goods and services to a typical consumer • Syn: ↑consumer price index, ↑CPI • Hypernyms: ↑price index, ↑price level …   Useful english dictionary

  • cost-of-living index — noun Date: 1913 consumer price index …   New Collegiate Dictionary


We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.