Ask the Independent: How do I decide who to vote for?

How do I decide who to vote for? Anna Evans, Retford

Voting is, of course, a highly personal decision, and although academics know a lot about politics we would not presume to tell which party would be the best to run the country or who to vote for.

However, we can describe what voters usually look at when deciding how to vote.

In their book Elections and Voting, Dr Martin Harrop and Professor William L Miller argue that there are three main factors that explain electoral behaviour: party identification, sociological and rational choice.

Party identification suggests that people vote according to how they see themselves: thus you identify with, and see yourself as, "Labour" or "Tory" or "Lib Dem" and vote accordingly.

The sociological approach is similar but argues that voters base their decision on a sense of belonging to a group in society. Thus you vote for the party which best represents the interests of that group. This can be seen in the close association of Labour to the working classes and Tories to the middle and upper classes.

Rational choice is a much more strategic approach and considers voting to be a choice about what candidate or party would best satisfy your particular interests. A voter would therefore assess the performance of the Government and compare it to an estimation of how the Opposition would perform if they were in power. The choice is then based upon which potential outcome would protect your interests the best.

These approaches are only models and Professor Cees van der Eijk at Nottingham University argues that the decision process of whom to vote for is a mix of them all. He sees three stages in this process.

The first thing is to search for a party that has a similar outlook on the world as you, in terms of your priorities, interests and visions for the future. This is to find a party identification according to your or your groups' interests.

This identification process usually leaves an individual with only a few parties to choose between, and the second stage in the decision-making process is to assess which one of these parties is most competent and most likely to actually be able to promote your interests, i.e. you are making a rational choice to promote your interests.

The third and final stage is even more strategic and is to consider whether your preferred party will actually stand a chance of winning, to avoid wasting your vote.

My individual vote won't make a difference to the result. Why should I bother? Phillip Moxley, North Newbald

We can stream off a list of generic reasons to vote: it is a civic duty comparable to other duties such as jury duty; parliament reflects more accurately the "will of the electorate" if there is a high turnout; and without a sufficient turnout a government's legitimacy is called into question.

These arguments are used in Australia by those who defend the compulsory vote. But it's not compulsory here. We don't incur a penalty and our vote may not count anyway depending on which constituency we vote in and which party we support. So, where's the draw?

This highlights the voter's paradox: it is rational to assume your vote will have little impact in an election. However, if everyone thinks this way then no one would vote and there would be no election. David Runciman suggests the problem is we are "too used to thinking about voting in terms of what's in it for the individual – the assumption being that people put something into the voting system in the hope of getting something out".

There is nothing particularly wrong with wanting to get something out of casting your vote. Mancur Olson in 1965 in The Logic of Collective Action introduced the problem of "free riding": individuals riding on the back of the rest of the electorate – if everyone did that there would be no voters.

There is, Runciman says, a difference between one person trying to "hold back a flood with a bucket" and only one person turning up to the polling station: whereas the person with the bucket would appear foolish in their futile attempt, if only one person went to the ballot box their vote would not be futile but would decide the election. This could inspire others to vote "if only to prevent that individual from deciding for everyone else".

Richard Tuck, of Harvard University, writes that there is a "threshold" where a party, in numerical terms, only needs one more vote in order to win a seat. So, if you happen to be that one voter who enters their voting slip into the ballot box at the point when this threshold is reached, then your vote could be the deciding vote. However, what about the people that voted before and after? This could then show that these votes were wasted. However, as Professor Tuck explains, without the preceding votes no threshold will be reached. Therefore, every vote counts.