In a recent research, four European Central Bank economists found that negative interest rate policy in the eurozone can encourage banks to increase lending and encourage cooperations to increase investments.
That is, contrary to what macroeconomics models usually predict, interest rate policy can still has stimulative effect even the zero lower bound is reached.
>Professor Olivier Blanchard further explained the role empirical research on DSGE models, how to teach undergraduates macro after the Great Recession, and his research on hysteresis.