Five threats to American prosperity tie the hands of its banker-in-chief

Janet Yellen, the head of the Federal Reserve, has been criticised for dithering, but there are many factors stopping her from raising interest rates

When Janet Yellen sits down with her colleagues on the Federal Reserve's interest rate-setting committee this week, another slice of her credibility will be on the line.

America's recovery since the financial crash has not followed the path it was supposed to. The central bank's constant dithering over whether to raise interest rates has made it appear weak and unable to influence events.