The Producer Price Index (PPI) is the official measure of producer prices in the economy of the United States. It measures average changes in prices received by domestic producers for their output. The PPI was known as the Wholesale Price Index, or WPI, up to 1978. It is published by the Bureau of Labor Statistics and is one of the oldest economic time series compiled by the Federal government of the United States. The origins of the index were in an 1891 U.S. Senate resolution authorizing the Senate Committee on Finance to investigate the effects of the tariff laws "upon the imports and exports, the growth, development, production, and prices of agricultural and manufactured articles at home and abroad". The PPI for Final Demand is the headline index of the PPI News Release. It measures change in prices received by domestic producers for goods, services, and construction sold for personal consumption, capital investment, government, and export. Most of the data for the PPI is collected through a systematic sampling of producers in manufacturing, mining, and service industries, and is published monthly by the Bureau of Labor Statistics. Virtually every type of mining and manufacturing industry and a majority of service industries are sampled. Survey respondents participate voluntarily. The data provided by respondents to the BLS is strictly confidential, protected by the Confidential Information Protection and Statistical Efficiency Act (CIPSEA) of 2002. Classifications The Producer Price Index family of indexes consists of several classification systems, each with its own structure, history, and uses. However, indexes in all classification systems draw from the same pool of price information provided to the Bureau by survey respondents. The three most important classification structures are industry, commodity, and final demand-intermediate demand (FD-ID). Industry The PPI for an industry measures the average change in prices received for an industry’s output sold to another industry. For more than 20 years, the PPI used the Standard Industrial Classification (SIC) system to collect and publish data. This system received criticism for its inability to adapt to changes in the United States economy. Consequently, in January 2004, the BLS began to publish the PPI data in accordance with the North American Industry Classification System (NAICS). This system was developed in cooperation with Canada and Mexico, and categorizes producers into industries based on the activity in which they are primarily engaged. Commodity A PPI from the commodity classification system measures change