The presumption is that the central bank will stop its bond purchases before it begins to raise its policy rate. That does not mean that the day the bond purchases stop is the day that the policy rate increases. There may well be quite a period of time between those two actions. Rather, it is a statement about the sequencing of policy actions.
Since the financial crisis, there has been a program of research into the effects of bond purchases or QE. Recently, I was involved as an external adviser in a review by the Bank of England of its QE Program. [13] That review summarised the state of the research into the effects of quantitative easing.