What would happen if all the analysis of this election omitted Scotland? Or if the polls that increasingly inform our understanding and analysis of politics decided it wasn’t worth examining the views of those aged 18-24? How about if journalists decided that they should ignore Liberal Democrat supporters, irrelevant as we know how they’re going to vote? There would be some outrage, surely.

Yet there is a glaring absence in our existing political analysis: ethnicity. This despite the fact that there are more ethnic minority voters than Scottish voters, Liberal Democrat voters, or 18 to 24-year-old voters. In an election where tactical voting is widespread, such polls and reporting may even be shaping how people vote.

There are now around five million ethnic minority voters in Britain, and ethnicity is perhaps the strongest predictor of vote choice: more than class, more than age, and even more than education. Polling is one of three reasons why we haven’t seen enough political analysis of ethnic minority voting. Journalists don’t see ethnicity breaks in polls, and even at a constituency level are not addressing the possibility that the pronounced Labour-lean among ethnic minority voters might be affecting outcomes.

For example, even the best polling from the 2017 election, YouGov’s MRP model, which alone predicted a hung parliament, still underestimated the Labour vote share in the constituencies with the most ethnic minority voters. While this didn’t affect any individual seat calls, it did suggest that seats were more marginal in places such as Battersea and Edmonton than results indicated.

There is an assumption that it’s only the most diverse seats where ethnicity is a factor, and these seats are all safe Labour anyway. While it’s true that Labour holds 69 of the 73 most diverse seats in Britain, they have only become this diverse and Labour-supporting recently. Until the 1980s there were no seats with more than 30% ethnic minority populations, the point at which seats become difficult for the Conservatives to hold. There are now over 75 such seats. Seats that were safe Conservative in the 1980s have become safe Labour today (eg Brent North, Birmingham Hall Green), in large part because of the large rise of the ethnic minority population in those seats.

‘Hundreds of seats that are less diverse, such as Thurrock, Cambridge, St Albans (above) and Sheffield South East, have risen from a BAME population of 4-10% in 2001 to 8-18% in 2011.’ Photograph: David Richards/Alamy Stock Photo

But it’s not just highly diverse seats where ethnic minorities can make a difference, and where ignoring their political behaviour affects our analysis of the election. Hundreds of seats that are less diverse, such as Thurrock, Swansea West, Cambridge, St Albans, Sheffield South East, Stoke-on-Trent Central, Gloucester, Wokingham and Bromley and Chislehurst have risen from a BAME population of 4-10% in 2001 to 8-18% in 2011. Runnymede has previously estimated all such seats will exceed 11% by 2021, with many reaching a BAME population of 20-25%, which indicates the need for candidates to understand and represent these constituents outside Britain’s metropolitan areas.

If we are to solve this problem, polling companies must do a better job of collecting data on ethnicity. It’s true that sampling ethnic minorities would be costly, but it’s also true that private companies are paying millions of pounds to Britain’s pollsters, and that those pollsters are influencing the nature of our democracy, and whose voices and interests count most. With ethnicity such a strong predictor of vote choice, the current lack of ethnicity breaks is increasingly indefensible.

But even if the pollsters continue to drag their feet, journalists need to improve their understanding of race and ethnicity in Britain today. We can see the low level of interest in the way that racism is discussed generally, as an attribute of individuals, or as part of a sensationalist story about celebrities, rather than as a systemic or institutional issue with deep historical roots in our society. Where are the vox pops with young black voters? Where are the editorials about the “genuine concerns” of Asian working-class men?

This is both a question of basic data, but perhaps more importantly about understanding the nature of ethnic minority communities in today’s Britain, and of racism. Even without data we have no shortage of journalists touring the country and meeting voters, but there’s been little curiosity about ethnic minorities and their views about Brexit, racism, the NHS or the economy – or anything much at all.

Ethnic minorities in Britain are well aware that their voices are not heard. They see it every day on their televisions and in their workplaces. The current weakness of our political analysis of race and ethnicity in Britain isn’t just a failure of research or political analysis. It’s a failure of equal representation in our democracy.

• Omar Khan is director of the race equality thinktank the Runnymede Trust