A lot of things have been said about those who have not made their minds up yet with regards to whether they will vote yes or no in this year’s referendum on Scotland’s constitutional future.

Sometimes those undecided have simply been declared as those who probably do not care at all and are therefore not likely to think about it – and who will probably not turn out. On other occasions links to a range of socio-demographic variables have been made suggesting that people from particular backgrounds, in particular those from lower socio-economic backgrounds would be less likely to make up their minds.

But very few of these propositions have been backed up with actual data.

SSA

Using the representative 2013 Scottish Social Attitudes Survey (SSA) we have been able to properly investigate what characterises those undecided. We found a lot of the commonly expressed assumptions paraphrased above could not be supported.

But about one-third of voters say that they have not made their mind up yet. Therefore it is worth engaging with them in more depth to properly understand their reasons for indecision.

Age, sex and class

First of all, demographic differences do not show major differences in the likelihood of being undecided. There is no consistent age pattern – most age groups are similar to one another. While those older than 65 appear to be a little more decided and those 25-34 a little less, none of these differences are actually robust when you account for other influencing factors at the same time, such as sex and social class.

SSA

Similarly there are no major differences in decidedness between different social classes. Most are very similar, with those that may be considered about in the middle (small employers and own accounts workers) being slightly less likely to be undecided and those in lower supervisor and technical occupations being slightly more likely. But there is no clear pattern. The percentage of those undecided is effectively the same for those in the highest and those in the lowest social class (at 35 and 36% respectively).

Again, when controlling for other demographic factors we do not find the relationship between social class and decidedness to be robust.

SSA

There is a small relationship between indecision and general political interest. A small group of politically very disinterested people (about 10% of respondents overall) has a substantially greater likelihood not to have made up their mind. These “usual suspects” indeed exist, but they are only a small proportion of all those undecided. Whether people have more or less interest in politics only relates marginally to their likelihood of having made their minds up.

Political interest only matters at the extremes. So many of the undecided voters are not disengaged, but can be identified by other factors.

SSA

There are some differences between men and women, with women being somewhat more likely not to have decided yet. This is a robust finding when taking into account other demographic variables, but the difference can be explained when we look at whether people think they know enough about the issue.

Those who feel that they do not have enough knowledge about independence yet are more likely to be undecided – and women are more likely to report the desire to know more about independence before deciding.

SSA

Those who feel independence would affect their lives more significantly are more likely to have made up their mind. So campaigns for both sides have been given a clear message – and a strategic approach would need to clarify this indecision on how independence would affect potential voters on each side.

Playing politics

Indecision is greatest among those who do not identify with any political party (at 48% indecision). This makes some sense, as those voters are probably not receptive to the clear pointers that the various political parties are providing. But there are also differences between parties in the campaigns. While nearly all those who identify as Conservative and Liberal Democrat have made up their mind (89% and 85% respectively) Labour identifiers, show similar levels of indecision to SNP identifiers (36% and 35% respectively), despite Labour being part of the Better Together campaign.

There is one more important group of undecided voters the campaigns should pay close attention to: those who do not have their favourite option on the ballot paper.

SSA

Approximately one third of respondents in the survey stated their most preferred option for Scotland would be further devolution (commonly referred to as “Devo Max”). Among the Devo Max-inclined voters, 45% were still undecided (compared to only 30% among those who preferred other constitutional solutions). Neither campaign has been able to capture a large number of potential voters who would have preferred further devolution to either independence or continuing full union.

If they want to reach these people, they will have to convince them that their proposals come closest to the preferred option of these voters.

The Yes campaign would presumably have to convince them that a No is unlikely to result in substantial further devolution, while the Better Together campaign would have to persuade those people of the opposite, that a No would be followed by effective further devolution.

If either campaign is able to do this we may see a relevant number of those undecided still shift correspondingly.

Hard Evidence is a series of articles in which academics use research evidence to tackle the trickiest public policy questions. The graphics were reproduced with the kind permission of ScotCen Social Research.