Just in case you were wondering what other reasons the Fed could have for using QE -- well here is a pretty good one. The flowchart below shows the effects of the Fed's QE on other world economies and supplies us with a very good reason why these foreign economies might initiate a currency war for their own economic survival.
The above also goes a long way to help explain the current weird economic disconnect between an upwardly mobile US Stock Indices versus high US unemployment and a God-awful Real GDP of -1%, as well as a barren Mainstreet -- still a dollar desert in deflation. And currently, about $1.5 billion dollars are leaving American shores and flying abroad every day.
This flowchart would also seem to successfully and completely trash any such fickle theories on the effectiveness of "Trickle Down Economics" by the Keynesians.