Short-Term Integrated Forecasting System (STIFS)
STIFS is used to generate short-term (up to 8 quarters), monthly forecasts of U.S. supplies, demands, imports, stocks, and prices of various forms of energy. The STIFS model consists of over 300 equations (excluding equations used to convert standard units into energy equivalents such as British thermal units (Btu's)), of which just over 100 are estimated. The estimated equations are regression equations that together form a system of interrelated forecasting equations. The selection of functional form and the estimation technique is generally done on an equation-by-equation basis. The general method of estimation is ordinary least squares. Some equations incorporate a correction for autocorrelation of the error term.
Petroleum Products Supply Model Description:
The driving forces in the Petroleum Product Supply Model are estimated refinery inputs and refined product demands. Estimated refinery outputs of individual products yield share weights with which to disaggregate total refinery inputs. Net product imports and inventory change bear the burden of balancing product supply with product demand.
Petroleum Products Demand Model Description:
Nonutility petroleum products consist of the following: motor gasoline, jet fuel, nonutility distillate fuel oil, nonutility residual fuel oil, liquefied petroleum gases (LPGs), and other (minor) petroleum products. The major determinants of demand for these products are: transportation activity, economic activity (i.e., gross domestic product, transportation activity, manufacturing output, etc.), prices and weather. Most of the estimating relationships incorporate monthly seasonal dummies and dummy variables (Dxxxx) to capture one-time events or conditions.
Utility demand for distillate and residual fuel oil is derived separately through simulation of the electricity model (see Electricity Supply and Demand section).
"Other" Petroleum Products Demand Model Description:
Most discussion on petroleum product demand focuses on the five major products used in the transportation, residential, commercial, and utility sectors: motor gasoline, jet fuel, distillate fuel, residual fuel, and liquefied petroleum gas. However, the third largest category of product demand is "other" petroleum products, which is made up of 14 different products and represents about 14 percent of total petroleum product demand.
Energy Prices Model Description:
The prices are important in their own right, because they are widely used for budget planning and other purposes by Federal and local government agencies, as well as corporate planners. These prices are also used in the projections of energy supply and demand.
Electricity Model Description:
The STIFS model determines monthly aggregate U.S. electricity demand by four major sectors and provides a national-level supply balance. In STIFS, U.S. electricity supply is comprised of two major components: domestic net electricity generation (that is, electric power actually transmitted to the transportation grid by electric utility-owned and nonutility-owned power plants) and net electricity imports (principally from Canada). Generation sources (fuels used in power production) identified in STIFS are coal, petroleum, natural gas, nuclear power, hydroelectric and other renewables, including wind and solar, wood and waste, and geothermal. A catchall category representing the total of transportation and distribution losses of electricity and other items, including any pure statistical discrepancy between electricity supply and electricity demand, rounds out the demand/supply balance.
Coal Model Description:
The STIFS model determines total coal consumption as the total demand for four major sectors: electric utilities; coke plants; retail and general industry; and coal consumed by independent power producers.
Natural Gas Model Description:
Natural gas demand is calculated for six sectors, including four major consumption or end-use categories as well as estimated consumption of natural gas by pipelines and natural gas consumption by gas field and natural gas plan operations. In addition, a small amount of gas exports is accounted for. Weather (particularly in the residential and commercial sectors), household formation (residential sector), commercial employment (commercial sector), natural gas prices relative to competing fuel prices, and industrial output (industrial sector) are all important factors in the short-term determination of natural gas demand.
Last Model Update:
Part of Another Model?
Archive Media and Installation Manual(s):
STIFS0199-STEO, October 1999.
Non-DOE Input Sources:
Most of the data sources provide monthly data and are used directly. Quarterly data are interpolated into monthly series.
DOE Data Input Sources:
The historical energy data used to estimate the model come primarily from the IMDS electronic database. IMDS merges data regularly reported in several EIA publications: Quarterly Coal Report, Petroleum Supply Monthly, Petroleum Marketing Monthly, Electric Power Monthly, Natural Gas Monthly, and Monthly Energy Review. Because of data limitations there are inconsistencies in the level of disaggregation of each type of fuel. For example, electricity and natural gas demands are represented by market sector, but petroleum products are generally represented only as national totals or for a combination of sectors (distillate and residual fuel oil are exceptions). Market-level data are available for the regulated industries (electricity and natural gas) while product-level data are available for the petroleum product markets, particularly for data frequencies higher than annual.