That’s when I was saying L shaped recover rather than V or even U shaped:
Janet Yellen, 2009:
My forecasts for output and employment are similar to the Greenbook’s, so I won’t go into the details. I do want to emphasize that I anticipate a rather sluggish recovery, not the rapid V-shaped recovery we have frequently seen following deep recessions in the past. The process of balance sheet repair that households and financial institutions are undergoing will result in subdued spending for an extended period, and monetary policies here and abroad are not able to play as big a role as usual in promoting recovery because of the constraint of the zero lower bound on short-term interest rates.