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A Comparison of Measures by Consumption and Supply Surveys

June 15, 1988

Energy policy makers-be they industry executives, members of utility commissions, or government officials require reliable data to make informed decisions. The need is particularly acute when the task is to forecast the future of energy markets. Making reasonable estimates of possible future prices, supply, and demand for energy requires accurate and detailed data about the current and historical situation of energy markets.

The Energy Information Administration (EIA) was mandated by Congress to be the agency within the Department of Energy that collects, analyzes and disseminates impartial, comprehensive data about energy-how much energy is produced, who uses it, and the purposes for which it is used. Energy data are also collected by a wide range of other groups; including other governmental agencies Federal, State and local; individual utility companies; and members of the energy industry, including individual companies and industry associations, such as the Edison Electric Institute.

To forecast energy market behavior, it is useful to bring together as much data as possible about the supply and demand of energy. The integration of data on the same subject from different sources, however, usually entails some difficulty since data collected by different groups and/or by different means are seldom completely compatible. Some effort must therefore be undertaken to reconcile the differences in data sets before the combined data can be used in an analysis.

EIA collects data from two distinct sources that, in their entirety, provide a comprehensive picture of energy production, marketing and use in the United States. The first set of surveys- termed "supply" surveys in this report-are directed to the suppliers or marketers of specific fuels (including electricity). These surveys measure the quantity of the specific fuel produced and/or supplied to the market, along with other information related to the fuel's production and supply. Supply surveys are conducted for petroleum, natural gas, electricity, and coal. (The "supply" surveys for coal include surveys of consumers, which provide information on coal consumption; these surveys are discussed in the chapter on the industrial sector.)

The second group of surveys-termed "consumption" surveys in this report-collect data from samples of end-use consumers. These consumers use one, several, or all kinds of fuels. These surveys gather information on the types of fuels used by the consumer, the purposes for which each fuel is used, and the characteristics of the users. The end-use consumption surveys are conducted for the residential sector, commercial buildings, manufacturing establishments, and personal transportation.

Together, the uata from the supply and consumption surveys provide a ncn, aeianeu source or data on energy supply and use. The supply surveys have been conducted for many years, starting with predecessor agencies to EIA, The consumption surveys were started during the past decade under the auspices of EIA.

It is tempting to merge the time series data from the supply surveys with the detailed cross- sectional data from the consumption surveys. However, there are important differences between the supply and consumption surveys which need to be taken into account in any analysis that uses both data sources.

This report discusses the relationship of EIA data from the supply surveys and from the consumption surveys. This comparison is made for three major end-use sectors: residential, commercial, and industrial. The discussion of industry is limited because the consumption survey covers manufacturing industries while the supply surveys (with the exception of coal) cover the entire industrial sector. No discussion is given of the transportation sector because the end-use consumption survey collects data only for personal transportation, and there are no comparable supply data available. Estimates of energy supply and consumption in each sector are compared for electricity, natural gas, petroleum fuels, and (for manufacturing industries) coal.

It is tempting to merge the time series data from the supply surveys with the detailed cross- sectional data from the consumption surveys. However, there are important differences between the supply and consumption surveys which need to be taken into account in any analysis that uses both data sources. This report discusses the relationship of EIA data from the supply surveys and from the consumption surveys. This comparison is made for three major end-use sectors: residential, commercial, and industrial. The discussion of industry is limited because the consumption survey covers manufacturing industries while the supply surveys (with the exception of coal) cover the entire industrial sector. No discussion is given of the transportation sector because the end-use consumption survey collects data only for personal transportation, and there are no comparable supply data available. Estimates of energy supply and consumption in each sector are compared for electricity, natural gas, petroleum fuels, and (for manufacturing industries) coal. There are three important differences between the supply-based and consumption-based surveys:

  • The supply surveys measure product supplied at some point in the supply chain, while the consumption surveys measure the actual quantity of fuel consumed (except for petroleum fuels for which the quantity delivered to the consumer is measured). Since fuels (except electricity) can be stored, the amount of product supplied to a sector in a given period is not necessarily equal to the amount consumed.

  • It is tempting to merge the time series data from the supply surveys with the detailed cross- sectional data from the consumption surveys. However, there are important differences between the supply and consumption surveys which need to be taken into account in any analysis that uses both data sources. This report discusses the relationship of EIA data from the supply surveys and from the consumption surveys. This comparison is made for three major end-use sectors: residential, commercial, and industrial. The discussion of industry is limited because the consumption survey covers manufacturing industries while the supply surveys (with the exception of coal) cover the entire industrial sector. No discussion is given of the transportation sector because the end-use consumption survey collects data only for personal transportation, and there are no comparable supply data available. Estimates of energy supply and consumption in each sector are compared for electricity, natural gas, petroleum fuels, and (for manufacturing industries) coal. There are three important differences between the supply-based and consumption-based surveys: The supply surveys measure product supplied at some point in the supply chain, while the consumption surveys measure the actual quantity of fuel consumed (except for petroleum fuels for which the quantity delivered to the consumer is measured). Since fuels (except electricity) can be stored, the amount of product supplied to a sector in a given period is not necessarily equal to the amount consumed. The consumption surveys are based on a sample of the consumers in each economic sector, so there is a sampling error associated with the data from these surveys in addition to the nonsampling errors that are common to both sample and census surveys. In many cases, the supply surveys are a census of suppliers and so have no sampling error.

  • There are differences between the consumption and supply surveys in the coverage of each sector. The residential consumption survey, for example, does not cover the same set of residences as do the supply surveys. Further, there are differences among the various supply surveys in the coverage of each sector.

These differences are discussed further in the next chapter. It is important to note that the existence of differences between the two types of surveys does not mean that one or the other is incorrect or improperly conducted. In both types of survey, the decisions on the kinds of data to gather and the means to collect them have been based on sound statistical criteria and a full understanding of the types of data that could be collected without placing an undue burden on the respondent. For the most part, the differences between the two types of surveys reflect limitations imposed by efforts to minimize the burden of responding to the surveys and the need to limit the costs of data collection.

The result of the comparison in this report shows that, taking into account their differences, the two types of surveys present a consistent picture of energy consumption in the United States. Neither type of survey alone provides a complete description of energy consumption by economic sector. A fuller understanding of energy use by sector can be obtained by using data from the two sources, allowing for their differences.

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