The competitive edge of the United States economy has eroded sharply over the last decade, according to a new study by a nonpartisan research group.

The report by the Information Technology and Innovation Foundation found that the United States ranked sixth among 40 countries and regions, based on 16 indicators of innovation and competitiveness. They included venture capital investment, scientific researchers, spending on research and educational achievement.

But the American economy placed last in terms of progress made over the last decade. “The trend is very troubling,” said Robert D. Atkinson, president of the foundation.

Measuring national competitiveness and the capacity for innovation is tricky. Definitions and methods differ, and so do the outcomes. For example, the World Economic Forum’s recent global competitiveness report ranked the United States first. Much of the forum’s report is based on opinion surveys.