Federal Reserve Chair Janet Yellen on Thursday touted the strength of the United States economy, rebuffing some political rhetoric suggesting a bubble is ready to burst. "I certainly wouldn't describe this as a bubble economy," Yellen said, noting a "healing" labor market and a 5 percent headline unemployment number. Yellen appeared on a panel with former Fed Chairs Ben Bernanke, Paul Volcker and Alan Greenspan at the International House in New York. The U.S. central bank heads discussed the U.S. economy and monetary policy around the globe. Yellen's comments come amid Republican presidential contender Donald ... (full story)