‘New poll suggests…’: How to tell when public opinion has really changed

The volume and frequency of opinion polls in the UK has increased enormously since the advent of online polling in the early 2000s, bringing with it heightened scrutiny of potential changes in public sentiment on political and social issues. Polls measuring vote intention are now published on an almost weekly basis, even outside election campaigns. And, as the negotiations over the UK’s withdrawal from the European Union edge toward their conclusion, polls on public attitudes toward the rights and wrongs of Brexit and the possibility of a referendum on the government’s negotiated deal feature almost as regularly.

Whenever a ‘time-series’ poll of this kind is published, commentators are faced with the difficulty of determining whether a change of a few percentage points in a particular direction is due to true change in public opinion, or whether it simply reflects the random variability we should expect to see between any two samples. CONT.

Patrick Sturgis & Jouni Kuha, LSE Politics & Policy