Yes-word bias?

At the time of the first independence referendum, I was a lone voice complaining that it was biased in favour of a Yes response because people prefer to be seen as positive rather than negative and thus tend towards answering Yes over No.

Five years later, and Keith Howell from West Linton writing in a letter to The Scotsman makes a similar point. Scotland has many august universities, yet none of the social scientists working in those universities voiced any complaint about the Yes bias in 2014.

To ensure that a question is not biased in favour of Yes it needs to be tested prior to any referendum. Why didn’t any social scientists working in Scotland voice concern about the Yes bias?

We all have cognitive biases, one of which is “herd effect”. The Yes effect could cause as much as a 3 per cent bias in favour of the answer Yes. Which is why [Scottish Cabinet Secretary] Mike Russell is adverse to changing the question.

Mike Russell is not in favour of honestly obtaining the view of the people of Scotland – he is solely interested in obtaining independence (“Confirmation bias”).

NEIL SINCLAIR Clarence Street, Edinburgh

Despite UK government spin, it seems Northern Ireland is getting a special deal to effectively remain in the EU Customs Union, which means the end of a UK single market.

Northern Ireland will then have an unfair trading advantage over businesses in Scotland, including our fishermen and farmers whom the Tories claim to represent. They are expendable, just as the Tories said when the UK negotiated to join the EU in 1973.

Such a deal is even worse for Scotland than Theresa May’s best efforts and an insult to our Scottish Parliament that backed SNP proposals for the UK to remain in the Customs Union and the EU single market.

Voters in England, Wales and Northern Ireland are getting the Brexit outcome they voted for but not Scotland as an equal partner in the Treaty of Union, despite recording the highest vote to Remain.

The proposed Irish customs plan will hasten the reunification of Ireland and accelerate demands for Scotland’s future as a self-governing nation in or out of the EU.

MARY THOMAS Watson Crescent, Edinburgh