什么是物价指数

一组价格的变化量数，包含一系列数字，目的是要对两个时间或地点之物价进行比较，以显示两个时间的物价变化、或两个地点的物价差异。物价指数是最早发展出来的生活支出变化量数，为的是要决定如何调整可维持基本生活水准（standard of living）的工资。物价指数主要有两类，第一类是拉斯皮尔制定的拉氏指数（Laspeyres-type indexes），先选定某一基期内的财货市场组合，再利用其物价来检定该财货在不同时空的物价变化，计算出该财货今日价格和基期价格的比例。拉氏法有两种最常用的指数，分别是消费者物价指数（consumer price index,CPI）和生产物价指数（producer price index, PPI），其中生产物价指数旧称趸售物价指数（wholesale price index）。CPI测量基本财货（如食、衣、住）零售物价的变化，PPI则测量制造厂和趸售商出货价格的变化。第二种是裴奇所制定的裴氏指数（Paasche-type indexes），先选定当前的财货市场组合，再利其物价来检定过去时间同样财货的物价变化；裴氏法最常用的指数是国内生产毛额平减指数（GDP deflator），在美国用於国民收入会计，以计算经常货币总额与当前货币总额的差异。

price index

Measure of change in a set of prices, consisting of a series of numbers arranged so that a comparison of the values for any two periods or places will show the change in prices between periods or the difference in prices between places. Price indexes were first developed to measure changes in the cost of living in order to determine the wage increases necessary to maintain a constant standard of living. There are two basic types. Laspeyres-type indexes define a market basket of goods in a base period, then use the prices for those goods to examine change over space and time. In its simplest form, this is simply the ratio of what those goods cost today to what they cost in the base period. The two most familiar indexes of this type are the consumer price index (CPI) and the producer price index (PPI). The CPI measures changes in retail prices in such component parts as food, clothing, and shelter. The PPI (formerly called the wholesale price index) measures changes in the prices charged by manufacturers and wholesalers. Paasche-type indexes define a market basket of goods in the current period, then use the prices of those goods from past periods. The most familiar index of this type is the GDP deflator, used in the U.S. in the national income accounting to differentiate amounts in constant dollars from those in current dollars.