There are a set of five economic indicators that have been guiding U.S. economic policy for decades, but most are not understood by the average citizen and, Mr. Karabell argues, are not as relevant today as when they were created. Gross national product, balance of trade, unemployment, inflation and consumer confidence should no longer be the primary basis for business plans or monetary policy, he says, as the technology revolution has made considerably more data available. He talks with Wall Street Journal reporter Kimberly Strassel.