Election poll tracker: How do the parties compare? – BBC News

All polls are based on a sample of people interviewed, typically more than 1,000, which is then weighted to be representative of the country.

There is always a margin of error, meaning the real percentage could be higher or lower than any one poll suggests.

We estimate that the true support for each party lies within the ranges shown here.

Each dot in the chart shows one poll result for a party.

We summarise all that information with an average line that makes it easier to understand the trend.

To get an appropriate range of polls for our averages, we use those conducted by members of the British Polling Council.

Its members agree to the same rules on transparency, but the council has said membership should not be seen as a guarantee of quality.

The polls we include have come from BMG, Deltapoll, Electoral Calculus, Find Out Now, Focaldata, Ipsos, JL Partners, More in Common, Opinium, Norstat (formerly Panelbase), People Polling, Redfield and Wilton Strategies, Savanta, Survation, Techne, Verian (formerly Kantar Public), WeThink (formerly Omnisis), Whitestone Insight and YouGov.

We only include the headline percentages on voting intention, which pollsters calculate by excluding those people who answered “don’t know” or “won’t vote”.

Most of the polls included cover Great Britain, although some do poll the whole of the UK. People surveyed do not get the option to choose parties which only stand in Northern Ireland.

We include data that is in the public domain. Some polling companies will not publish all data for all parties at the same time.

Where polling companies have stated in their data tables who their client is, we have included this in our table. It is common for polling companies to do their work for news organisations, television programmes and campaign groups.

The true position for the Conservatives and Labour might be within five percentage points of our average.

Nine out of 10 polls just before election day have been within that range of the eventual national vote shares in the 2010 to 2019 general elections.

The gap has been smaller for other parties which campaign throughout Great Britain, such as the Liberal Democrats, Green party and Reform UK (formerly the Brexit Party) and smaller still for the SNP and Plaid Cymru.

Our estimate of a party’s support is a rolling average of polls.

A party’s share on any given day is the average of their results from polls taken over the previous fortnight. We only take the most recent poll from each company for that day’s averages.

All opinion polls will differ a bit because they are interviewing different people. There are also other things that can lead to differences between polling companies. For example:

For voting intention, polling companies typically ask interviewees a question along the lines of: “If a general election were held tomorrow, which party would you vote for?”

Some polling companies have not given their interviewees the choice of some parties, including them within the “other” category.

For example, Reform UK, formerly the Brexit Party until 2021, has only been included as an option in every poll featured in our tracker since autumn 2022, while support for Plaid Cymru is included among “other” parties in polls released by Techne.

Produced by Grace Richardson, Scott Jarvis, Becky Rush, Allison Shultes, Libby Rogers, Daniel Wainwright, Aidan McNamee, Jana Tauschinski, Debie Loizou, Preeti Vaghela, Robert Cuffe, John Walton.