Image copyright Getty Images

The opinion polls have sown a fair amount of confusion during the referendum on the UK's membership of the European Union so far.

Some, mostly those conducted over the internet, have suggested that support for Remain and Leave is close to 50:50.

Others, primarily conducted over the phone, give the impression that Remain are clearly, if not necessarily comfortably, ahead.

But for all their differences, there is much on which the polls agree.

Above all, they paint much the same picture when it comes to who is more likely to vote Remain in a month's time and who is more likely to vote to Leave.

The picture they paint is of a country that is deeply divided over the issue.

For a start there is a major generation gap.

Every poll finds that a majority of younger people want to remain in the EU. Leaving aside those who say they don't know how they will vote (and there are increasingly fewer of them), on average nearly three-quarters of those aged under 25 say they back Remain. Only a quarter or so wish to leave.

But the older someone is, the more likely they are to want to leave. Consequently, amongst the over-65s almost three in five wish to head for the exit.

It seems that the generation that in the last EU referendum just over 40 years ago voted by two to one to stay in the 'Common Market' has changed its mind.

In contrast, those for whom the EU has always been part of their lives are apparently quite keen to stay.

But there is also another big difference - between a relatively well-off Britain that enjoys the fruits of a university education and a less well-off Britain that does not have any certificates of educational achievement stored somewhere in a cardboard box.

Image copyright AP Image caption Young people are more likely to vote to stay in the EU

This emerges in part in the difference in outlook between those whom the pollsters call the ABC1s - people with well-paid office jobs - and the C2DEs - those in typically more physically demanding but less well paid occupations.

All recent polls, whether done by the internet or by phone, suggest that a majority of the ABC1s will vote to Remain, while most C2DE voters will opt to Leave.

However, it is not so much the kind of job that people do that matters as much as what kind of educational experience they have.

This emerges from academic surveys, which unlike most opinion polls, regularly collect details of people's educational background.

The most recent British Social Attitudes survey, for example, found that those with no educational qualifications were two and half times more likely to want to "withdraw" from the EU than were those with a degree to their name.

Image copyright Getty Images Image caption The Leave campaign is also targeting younger voters

Meanwhile, another academic survey, the British Election Study, has demonstrated that there is another important difference in the pattern of preferences - between those who belong to one of Britain's ethnic minorities and those who describe themselves as "white".

In a very large internet poll this study found that those who said they were "white" were evenly divided between supporters of Leave and backers of Remain.

However, those from an ethnic minority background were around two to one in favour of remaining.

Immigration is, of course, a key issue in the referendum campaign, and younger voters, university graduates and those from an ethnic minority background tend to be less concerned about the number of people who have come to Britain in recent years.

Image copyright PA Image caption The 1975 generation have changed their minds

However, not only do different kinds of people look likely to vote differently on 23 June, but so also do different parts of the UK.

Back in 1975, Scotland and Northern Ireland were the two parts of the UK that were least keen on staying in the Common Market.

Now the polls suggest they are the ones most inclined to vote to Remain - in both cases perhaps by as much as about two to one.

Still, there is at least one distinction that is not much in evidence - between men and women.

They are as equally divided as each other on the issue. But doubtless there will still be many a family argument about the EU during the course of the next month.

John Curtice is Senior Research Fellow, NatCen Social Research, and 'The UK in a Changing Europe' initiative, and Chief Commentator at whatukthinks.org/eu.