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Here’s what would have happened if Brexit vote was weighted by age

Britain’s youngest voters will spend about 60 years living with the consequences of Brexit – even though the majority of them voted Remain. Wouldn’t it be fairer if their vote was worth more than the vote of someone with only a decade left to live?

This could be seen as a cheeky insult to the principle of “one person one vote”, but in light of the polling results on the EU referendum, I think a little thought experiment is in order. Of course, this is not intended to discriminate against older citizens – I examine it simply to play with and explore the meaning of “fairness” in our democracy. The generational divide of the Brexit vote has angered many voters and commentators, as well as spawning a new round of internet memes.

When you voted to leave the EU but you gunna die soon so it's not your problem

— Medieval Problems (@Medieval_Probs) June 24, 2016

But many were quick to note that the younger generation’s overwhelming preference for staying in the EU didn’t translate into a result, because a majority of them simply didn’t turn out to vote. Because of the secret ballot, we do not actually know how many did or didn’t. But a YouGov poll (tweeted by Sky data) estimates that only 36% of 18- to 24-year-olds cast their vote in the referendum.

And it gets worse. Turnout is measured as a proportion of “voting eligible” individuals – which means people who are on the electoral register. But available registration data indicates that almost 20% of the youngest age group had not even bothered to register in the first place. Which means voter apathy among young people is even worse than the polling data would have us believe.

So, what if we gave young people’s votes more weight, proportional to how long they had to live? Would such a system be enough to counter the levels of non-voting that were observed on June 23rd? Let’s do a little back of the envelope calculation on how the Brexit vote would have panned out under this alternative voting system.

Crunching the numbers

In order to do that, we need to understand the voting behaviour for each age group. The data is scant, but some estimates are available. Lord Ashcroft’s referendum day poll on who voted for each outcome is based on a survey of 12,369 people after they had voted. Sky data estimated voter turnout based on YouGov data for the same age groups. And finally, we have registration levels by age from 2014 from an Electoral Commission report, which we can top up with new registrations from the government’s Voter Registration Dashboard, to get the numbers up to date. Then, all we need is population counts and life expectancy estimates, which are available from the ONS.

When we put these all together, we get an overview of how the UK voted, broken down by age group. All areas in the chart below are proportional to the number of people in each group. We can see the familiar Remain-Leave pattern as it shifts with age. And note how the unregistered (black shaded) and non-voting (grey shaded) proportions become smaller and smaller as the voters get older. What this means is that, for example, while the 18- to 24-year-old group represents almost 11.5% of the adult population, it made up only about 5.7% of the voters. And of course, the opposite is true for the oldest age group.

Author's calculation

Now for the alternative weighting: using remaining life expectancy, we can calculate how many “years left to live” belong to each age group, and use them to weight the results. So the youngest age group, which is about 5.8m people, has over 350m years of life left to live between them. And that is 19.6% of all the years left to live in our new voting system. Meanwhile, the over 65s – which currently represent 22.6% of the adult population – only have 8.2% of the years left to live.

Here’s how our experimental voting system would work: the youngest group’s votes would account for 19.6% of the overall votes, while the over 65s preferences only make up 8.2%. So, with this new, “fairer” weighting of votes, would the result be radically overturned?

Well, it would be overturned. Remain would win with a two point margin. But the chart below shows even more dramatically how many “votes” are now lost to black and grey voter apathy.

Author's calculation

A good friend of mine called this system cruel. She noticed it implies that if you have one day left to live, your opinion doesn’t matter. She also knows of a solution: her grandparents have always asked her how they should vote, and then voted according to her wishes. If more people were as lucky as her, the system might take young people’s concerns into greater consideration.

The more our societies age, the more self-serving voting behaviour will translate into inter-generational warfare. To those who would argue that this would also be an ageist system: in fact, over an individual’s lifetime, everyone would get the same number of votes, so it would even out in the end. This thought experiment is not as fanciful as it may seem: political scientists in Japan – one of the oldest societies today – are already seriously theorising about how to put similar voting principles into practice. But until then, blaming the older generations for voting as they do, when the young don’t make use of their voting rights, is disingenuous at best.