The results of an opinion poll organized by Liverpool University and Britain’s Economic and Social Research have been published this week. The poll, carried out by Social Market Research, showed 29% of voters would vote for a united Ireland, with 52% against and 19% indicating that they don’t know or wouldn’t vote.

Polling on Irish unity over the last couple of years has painted a confusing picture. A poll commissioned by Lord Ashcroft last year was the first to show a narrow majority in favour of Irish unity, whereas the poll released this month would indicate a substantial majority against. Why are the polls showing such wildly different results?

The chart at the top of the post shows the results of opinion polls on Irish unity in Northern Ireland since the UK EU referendum in 2016. Polls conducted face-to-face are denoted by triangles, and online polls are shown as circles.

It is obvious from looking at this that there appears to be a significant difference between polls conducted in person and those carried out over the internet. It is also apparent that the difference is much more pronounced in the numbers saying they would vote for a united Ireland than those saying they would vote to stay in the UK.

Since 2017, the pro-union numbers have declined somewhat, but the “don’t knows” have broken substantially in favour of Irish unity. However, in the face-to-face polls, there is a substantial shift from pro-unity sentiment back towards being undecided.

So, is the discrepancy between online and face-to-face polls caused by people who are shy nationalists; people who are in favour of Irish unity when the question is between them and their web browser, but are more reticent when the question is asked in person?

To find out more about the “don’t knows”, I looked at the Northern Ireland Life and Times data from 2017, the last survey which had a border poll question.

Those who declined to express a preference on a border poll question tended to be from a Catholic (50%) rather than a Protestant (30%) background, with 20% being classed as neither. Of those who expressed a preference for a political party, the Alliance Party were the most popular party (34%) ahead of the SDLP (19%), Sinn Féin (16%), the DUP (11%) and the UUP (7%). This group were also much more concerned about the possible adverse impact on their finances due to Brexit, with 52% believing they will be worse off personally because of Brexit, as opposed to 34% among the population who expressed an opinion on Irish unity.

From analysis of the “don’t know” population from a face-to-face survey such as NILT, it seems reasonable to conclude that the undecided group contain a substantial number of what are often uncharitably characterised as the “latte drinking liberals”; middle class professionals who are deeply concerned about the potential negative impact of Brexit on the economy.

The fact that online polls are showing substantially higher support for Irish unification than polls carried out face-to-face, does seem to indicate a trend whereby centre ground voters are breaking towards support for Irish unity in private polls, but for whatever reason prefer not to disclose this in person.

The discrepancy between different categories of polls means that there are ample opportunities to cherry pick results that advance your particular point of view. However, it is worth re-iterating that social awkwardness isn’t a factor in real elections and referendums, which are of course carried out in secret.