[4] The latest data available on the state distribution of R&D performance are for 2004. In 2004, $283.4 billion of the $300.1 billion total U.S. R&D could be attributed to expenditures within individual states, with the remainder falling under an undistributed "other/unknown" category. Approximately equal shares of the R&D that could not be associated with a particular state were R&D performed by the nonprofit sector and by industry. State totals differ from U.S. totals reported elsewhere for four reasons: some R&D expenditures cannot be allocated to any of the 50 states or the District of Columbia; nonfederal sources of nonprofit R&D expenditures, totaling an estimated $7.1 billion in 2004, could not be allocated by state; state-level university R&D data have not been adjusted for double-counting of R&D passed through from one academic institution to another; and state R&D data are not converted from fiscal years to calendar years.

[5] Rankings do not take into account the margin of error of estimates from sample surveys.

[6] Federal intramural R&D includes costs associated with the administration of intramural and extramural programs by federal personnel as well as actual intramural R&D performance. This explains the large amount of federal intramural R&D reported within the District of Columbia.

[7] For most manufacturing industries, the Small Business Association has established a size standard of 500 employees. The NSF Survey of Industrial Research and Development does not sample companies with fewer than five employees because of concerns about respondent burden.