Some 40 percent of the nation's productivity and growth is unaccounted for in the gross domestic product (GDP), according to BEA Director Steve Landefeld. That's mainly because reliable data in some economic sectors simply don't exist. Using data from the National Science Foundation's (NSF) annual surveys of government, academic, industry and non-profit R&D expenditures, the U.S. Bureau of Economic Analysis determined R&D contributed 6.5 percent to economic growth between 1995 and 2002.

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