Artificial intelligence could be the most revolutionary force affecting productivity in the United States economy, says the president of the Federal Reserve Bank of San Francisco.

"Everyone in Silicon Valley thinks statisticians are mis-measuring the productivity provided by the internet, but it's not that," says John C. Williams, on a trip to Sydney this week.

The productivity gains from the inventions of electricity and the combustion engine had much more influence on humans' output capacity.

"Instead, the technologies that we now use and love mostly affect our consumption of leisure rather than affect our output in factories or offices."

Positive data showing the US economy is nearing full employment and that inflation is edging higher prompted the US central bank to recently raise interest rates for the second time in three months.