Westminster Voting Intention: Poll of Polls

End Date Company Client CON LAB LD UKIP GRN Lead
21 May 2017 ICM Online Guardian47 33 9 4 2 +14
20 May 2017 Survation Phone Good Morning Britain43 34 8 4 2 +9
20 May 2017 Survation Online Mail on Sunday46 34 8 3 1 +12
19 May 2017 YouGov Online Times44 35 9 3 2 +9
18 May 2017 ORB Online Telegraph46 34 7 7 +12
17 May 2017 Opinium Online Observer46 33 8 5 2 +13
17 May 2017 Ipsos MORI Phone Evening Standard49 34 7 2 3 +15
17 May 2017 YouGov Online Times45 32 8 6 2 +13
15 May 2017 Kantar TNS Online 47 29 8 6 4 +18
15 May 2017 Panelbase Online 47 33 7 5 3 +14
14 May 2017 GfK Online Business Insider48 28 7 5 3 +20
14 May 2017 ICM Online Guardian48 28 10 6 3 +20
13 May 2017 Survation Phone Good Morning Britain48 30 8 4 2 +18
12 May 2017 YouGov Online Times49 31 9 3 2 +18
12 May 2017 Opinium Online Observer47 32 8 5 2 +15
12 May 2017 ComRes Online Ind on Sun/Sun Mirror48 30 10 5 3 +18
11 May 2017 ORB Online Telegraph46 32 8 7 +14
10 May 2017 YouGov Online Times46 30 11 5 2 +16
09 May 2017 Panelbase Online 48 31 8 5 2 +17
08 May 2017 Kantar TNS Online 44 28 11 8 4 +16
07 May 2017 ICM Online Guardian49 27 9 6 3 +22
06 May 2017 Survation Phone Good Morning Britain47 30 7 5 3 +17
05 May 2017 ICM Online Sun46 28 10 8 4 +18
05 May 2017 YouGov Online Sunday Times47 28 11 6 2 +19
CON 46(46.5)
LAB 32(32)
LD 8(8.3)
UKIP 5(4.7)
GRN 2(2.1)

This is a rolling poll of polls, which is weighted so that a poll loses 0.05 of weighting every day after the end date of the survey (which isn't always the date it is published). Therefore, a poll where the fieldwork finished today has a weighting of 1, yesterday 0.95, 2 days ago 0.9, and so on. When a poll is 20 days old it has a weighting of 0, which means it will drop out of the poll of polls altogether.

In many ways, a rolling average of polls is not a foolproof method of determining the current positions of the parties - averaging good polls with bad won't produce better results - but it does give a better idea of the current trend of the polls than just taking the latest poll, which in itself has differences in methodology which could affect the headline figures. As such, the polls which the rolling average has been drawn from are included above, which is likely to highlight any outliers (which satistically happen every 20 polls on average), and you can draw your own conclusion about them - having said that, the outling polls make a very small difference to the overall poll of polls.