UK Election Data Vault

Voting Intention for 2024 UK General Election by Pollster

Pollster ratings included in parenthesis

Pollsters Ratings

Our pollster ratings are meant as a guide to recent performance of pollsters in UK general election polls. They are based on three components: accuracy, longevity and membership of the British Polling Council.

Seventy percent of a pollster’s score comes from their accuracy in predicting the most recent three UK general elections. The measure used depends on the differences between the national share of the vote (for the three largest parties) and the final poll fielded before polling day. A perfect prediction of each of the last three elections would contribute seventy points to a pollster’s score.

Ten percent of a pollster’s score comes from their longevity in polling UK general elections. A pollster is awarded ten points if the published a poll conducted during each of the last three parliaments (i.e. between 2015-17, 2017-19, 2019-24) New pollsters have a longevity score of zero.

Twenty percent of a pollster’s score comes from membership of the British Polling Council (BPC). Members receive twenty points and non members zero.

Pollster ratings are used in the calculation of our polling average. They have been back calculated so contemporary ratings are used to weight the poling average. For example, the pollster rating used to weight polls for the 2010 general election are based on accuracy in predicting the 1997, 2001 and 2005 general elections.

Calculation of pollster ratings

The calculation of our pollster ratings takes place in three stages. Firstly, we calculate accuracy of each pollster. To do this we take the last poll published before each general election and find the sum of squares of the differences between the poll result and final election result. Only polls taken in the final 60 days before an election are used in pollster ratings

We use polling results for Conservatives, Labour, Liberal Democrats, the SNP and Plaid Cymru. Each party has equal weight in the ratings, however, polling for the bigger parties tends to influence the final ratings more as the polling misses tend to grow with the vote share of a party. Table 1 shows the calculation of accuracy ratings for the 2024 general elections for Great Britain. We do similar calculations for polls in Scotland and Wales.

Table 1: Pollster Performance in 2024 general election

We do not base our pollster ratings purely on one election, we prefer to gauge accuracy in the longer term. Hence the second stage is to calculate an average trend rating over the past three elections. Table 2 shows the calculations for the latest trend ratings. All raw ratings have a floor of 25. In these cases either a pollster did not poll a particular election or they performed poorly in terms of accuracy.

Table 2: Pollster Performance in general elections 2015-2019

The final stage of the calcuation brings together the three elements of our ratings. In addition to accuracy, the other two elements are longevity and membership of the BPC. The Longevity weigtht is worth between 0 and 10 depending on how many recent election a pollster has polled. BPC members get 20 points and non-members get 0.

Final ratings are measured out of 100. Trend ratings are weighted down so they form 70% of the final rankings. They are then added to the longevity weight and BPC member weight to give the final raking score. These scores are given a letter grade to ease interpretation. Table 3 shows the calcuation of pollster ratings for all pollsters who polled the 2024 election.

Our highest ranked pollster at the moment is Opinium (Grade A-, Score 88) who have an accuracy rating of 83, along with full marks for longevity and BPC membership. The lowest ranked pollsters who are BPC members are PeoplePolling (D, 41 ) and FindOutNow (D, 41) who both have the lowest possible accuracy rating. Amoung pollsters who are not BPC members, Lord Ashcroft (D, 36) is the worst performer.

Table 3: Calculation of pollster ratings for next general election