Data Sources

Data Sources

The principal source for federal financial data is the Annual Budget of the United States Government published by the Office of Management and Budget (OMB). The numbers are consistent from year to year and follow the definitional structure required by OMB. The primary source for state and local government financial data is the U.S. Bureau of the Census. The Census Bureau conducts Census of Governments at five-year intervals for years ending in "2" and "7." The results of this Census provide comprehensive statistical information about state and local government financial activities. The data for census years are therefore full counts and not subject to sampling errors. Detailed data sources by mode and level of government are provided in Table 1.

In noncensus years, state and local data are collected through an annual survey, which is subject to sampling error. As reported by the Census Bureau, the data are generally subject to a sampling variability of less than 3 percent.

Federal data in this report correspond to the federal fiscal year, which begins on October 1, while state and local data are for fiscal years that generally start in July except for four states with other starting dates (Alabama and Michigan in October, New York in April, and Texas in September). While this may create a small error in totals for any given year, the data are suitable for illustrating trends in public transportation finance. The totals for transportation revenues and expenditures in this report are the sum of the Census Bureaus state and local data and the U.S. Budgets federal financial data.

Chained-Dollar Estimates

Chained-dollar estimates provide dollar values of government revenues and expenditures that are adjusted to remove the effect of changes in the level of prices. These estimates show the dollar values of revenues and expenditures, which would exist if prices had remained at the same average level as in the base period. They are computed by dividing the current dollar estimates by the chain-type price index and multiplying by one hundred (See Appendix II for definition of chain-type price index). The deflator used for federal revenues and expenditures differs from that used for state and local revenues and expenditures. However, the same deflators are used for expenditures and revenues. While a nondefense federal government chain-type price index is used to deflate current dollar federal revenues and expenditures, a state and local chain-type price index is applied for state and local government revenues and expenditures. If expenditures are totaled across different levels of government in chained dollars before and after federal grants, the totals do not match due to the difference in deflators used. All chained dollar estimates in this report are for the base year 1996, instead of 1992 as used in the previous editions of the report.

The price indexes are obtained from the National Income and Product Accounts Tables, Bureau of Economic Analysis (BEA), Table 7.1, Quantity and Price Indexes for Gross Domestic Product (available at http://www.bea.doc.gov/bea/dn/nipaweb/ as of October 2001). The Bureau of Economic Analysis produces separate chain-type price indexes for the federal, and state and local governments because of differences in the types of goods and services purchased.