Update: Well around noon, it looked — based on the “logic” of event studies — that Brexit was worth – 15% on the S&P, but by the close Brexit was worth -7%. With event studies, it depends on when you measure. This is a feature! It is important to look at if event studies support your thesis, and then if they do, choose them as a way of testing it. Given the variation in the results, there is always some window that works! The word for this among the academic quisling advocates of QE is “empiricism.”
So, as usual, the right-wing side has included some very violent people. The UK public has reacted to this and the perceived odds of Brexit have gone down about 8 percentage points over the weekend.
The FTSE is up 3.2% last I checked. So on the logic of an event study, Brexit would be worth 40% off the FTSE. On the logic of an event study, this would be taken as data or a “fact.”
This is the method people have used to infer the very high importance of QE. The trick is to decide ahead of time what result you want, and then to look around for methods to confirm your case. Among QE advocates, this is called “following the data” in a disinterested way to whatever conclusion it supports.