Voting Intention for Next UK General Election by Pollster

Pollster ratings included in parenthesis

Opinium (A-)

YouGov (A-)

Redfield & Wilton (D)

Ipsos-MORI (A-)

Savanta ComRes (B-)

Techne (D)

Survation (A-)

Deltapoll (D+)

Omnisis (D)

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 2010-15, 2015-17, 2017-19) 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 2019 general elections for Great Britain. We do similar calculations for polls in Scotland and Wales.

Table 1: Pollster Performance in 2019 general election

PollsterCONLABLIBSNPPLCSum of Squares of DifferencesRaw Rating
Opinium453312400100
Ipsos-MORI443312199
Kantar44321340397
Number Cruncher Politics43331241397
Panelbase43341140595
YouGov43341230595
Deltapoll45351040892
Survation45349411090
Focaldata423414311486
BMG4132141981
Savanta Comres413612402377
Election Result45331240
Party codes: CON-Conservatives, LAB-Labour, LIB-Liberal Democrats, SNP-Scottish National Party, PLC-Plaid Cymru

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

PollsterRaw Rating
2015
Raw Rating
2017
Raw Rating
2019
Trend Rating
(Average of
2015, 2017 & 2019)
Opinium857110085
Ipsos-MORI83719984
Kantar25909670
Number Cruncher Politics25259649
Panelbase52739272
YouGov52739172
Deltapoll25259247
Survation74929085
Focaldata25258645
BMG75288161
Savanta Comres84487769

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 2019 election and have published at least one poll since. Seven new pollsters have published a poll since 2019, six of them (Redfield & Wilton, Omnisis, PeoplePolling, More in Common, FindOutNow, Techne and JL Partners) are members of the BPC and have ranking score of 41 (D). The other new entrant (More in Common) is not a member of the BPC and has a score of 21 (F).

Our highest ranked pollster at the moment is Opinium who have an accuracy rating of 85, along with full marks for longevity and BPC membership. Amoung the pollsters who have polled at least one election before, the worst performing is Number Cruncher Politics with a score of 41 (D). This is mostly due to lack of longevity, they scored very well in the one election they have polled.

Table 3: Calculation of pollster ratings for next general election

PollsterTrend RatingTrend Rating
Weight
Longevity WeightBPC Member WeightFinal Ranking ScorePollster Grade
Opinium8560102090A-
Ipsos-MORI8459102089A-
Kantar7049102079B+
Number Cruncher Politics49347041D
Panelbase7251102081A-
YouGov7452102082A-
Deltapoll473372060D+
Survation8560102090A-
Focaldata453272058D+
BMG6143102073B
Savanta Comres6949102079B+