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EVALUATION AND REPORTING OF COUNTY GASOLINE USE METHODOLOGIES
Citation:
Kersteter, S. EVALUATION AND REPORTING OF COUNTY GASOLINE USE METHODOLOGIES. U.S. Environmental Protection Agency, Washington, D.C., EPA/600/R-94/003 (NTIS 94-145455), 1994.
Impact/Purpose:
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Description:
The report reviews two EPA studies that investigated improvements in the allocation of state-level gasoline sales to the county level in order to improve annual county-level emissions estimates from this source category. The approaches taken in these studies are compared with the current approach prescribed by EPA. The studies attempted to develop improved allocation procedures for estimating county-level gasoline sales using data for several states. The first study developed regression equations using county-level data to estimate county gasoline sales, while the second study analyzed proportional allocation methods using state- and county-level data to estimate county gasoline sales. Equations were developed using various demographic and vehicle-characteristic variables, and were based on 1986 data. Estimated county gasoline sales using the regression equations were generally closer to actual sales than gasoline sales predicted using the existing EPA approach. However, since some coefficients used in the regression equations were not statistically significant and since only 1 year of data were analyzed, these equations may not apply to years other than 1986. Using the proportional allocation approach, several variables were found to perform as well as the current EPA methodology. EPA methodology results consistently underestimated actual gasoline sales.