The vice president of the St. Louis Federal Reserve says the controversial practice of quantitative easing (QE) doesn't actually work that well, writing in a paper that QE theory is "not well-developed" and generates results that are "at best mixed."

Stephen D. Williamson, vice president of the St. Louis Fed, wrote his observations in a white paper dissecting the U.S. central bank's efforts to stem the financial crisis in 2008 and 2009. The effort was the largest financial stimulus program in the nation's history, swelling the Fed's balance sheet past the $4.5 trillion mark, reported CNBC.

QE is a practice in which the Fed electronically creates money out of thin air and uses it to buy assets such as government bonds in an attempt keep interest rates at zero, explains the Economist. Proponents of the practice, such as former Fed chairman Ben Bernanke, say QE stimulates the economy, stokes inflation and reduces unemployment, but Williamson questioned its effectiveness.

"All of [the] research is problematic as there is no way to determine whether asset prices move in response to a QE announcement simply because of a signaling effect, whereby QE matters not because of the direct effects of the asset swaps, but because it provides information about future central bank actions with respect to the policy interest rate," he said, reported ZeroHedge.

Along with muted inflation, gross domestic product still hasn't passed 2.5 percent for any calendar year during the recovery. As for wage gains and living standards, they have been stuck around 2 percent or less, according to CNBC.

Williamson continued to criticize Bernanke's approach to the financial crisis: "There is no work, to my knowledge, that establishes a link from QE to the ultimate goals of the Fed inflation and real economic activity. Indeed, casual evidence suggests that QE has been ineffective in increasing inflation. For example, in spite of massive central bank asset purchases in the U.S., the Fed is currently falling short of its 2% inflation target. Further, Switzerland and Japan, which have balance sheets that are much larger than that of the U.S., relative to GDP, have been experiencing very low inflation or deflation."

CNBC notes that the main place QE seems to have helped is the stock market, which has gone up 215 percent since the recession economy hit a low in March 2009. In other areas, people are worried about deflation and interest rates have stayed low.

In October 2014, the Fed quietly announced that it had ended the QE program, and it soon began trying to figure out how to sell the bonds back without creating panic in the market, according to the Guardian.