Nigel Marriott's Blog

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UK General Elections #8 – How accurate are voting intention polls? – updated with GE2024

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After their 2nd best ever performance in the 2019 UK General Election, the UK polling industry flipped in the 2024 UK General Election to their 2nd worst ever performance after 1992.  6 of the last 9 elections have seen at least one party experience a major polling error.  It would appear the move to web polling and lower barriers of entry has led to poorer quality polls.

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UK General Election 2024 #5 – My Final Forecast as of 3rd July 2024

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My third and final forecast of the number of seats to be won by each party in the 2024 UK General Election is –

  • CON 130 (+17)
  • LAB 420 (-17)
  • LD 50
  • SNP 25
  • GRN 3
  • PC 2
  • REF 2
  • OTH NI 18

The numbers in brackets are the changes from my second forecast of 30th June 2024.

This article is based on polling data as of 2000 on 3rd July 2024.  If more polling data comes in and causes me to change my forescript, the changes will be detailed in a postscript at the end of the article.

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UK General Election 2024 #4 – My Forecast as of 30th June 2024

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My second forecast of the number of seats to be won by each party in the 2024 UK General Election is –

  • CON 113 (+5)
  • LAB 437 (-5)
  • OTH 100 (unch)

The numbers in brackets are the changes from my first forecast of 23rd June 2024.

[Read more…] about UK General Election 2024 #4 – My Forecast as of 30th June 2024

UK General Election 2024 #2 – My Forecasting Model

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My UK General Election 2024 forecasting model will be a top down version which I last used in 2010.  Top down approaches first predict how many seats each party will win in total before seeking to identify which seats each party wins.  This differs from the bottom-up approach I used in 2017 & 2019 where I forecast the outcome for each seat first and then aggregated the forecasts.

Here I explain how my 2024 forecast will be made but it finishes with a warning that I may have to dump my 2024 model in favour of the forecasting approach I used for the 2015 general election.

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UK General Elections #7 – How accurate are voting intention polls? – Revised

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Voting intention polls in the UK are accurate after all!

For years, I’ve observed that UK polls on average underestimate the Conservative vote and overestimate Labour’s vote.  When I converted poll data into forecasts of seats won, I had to first estimate how much polling error there would be.  So what’s changed?  It turns out I was comparing polls to the wrong statistic, namely national vote share.  The correct comparator is in fact average vote share per seat.

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UK Weather Trends #31 – Spring 2024

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Spring 2024 in the UK was the hottest on record.  In some ways this is surprising given it was also the 10th dullest and 6th wettest spring on record which is inconsistent with trends over last 25 years and with the typical correlations seen in spring.  With any other dataset, I would ask for a check on the temperature data to see if it is correct.

[Read more…] about UK Weather Trends #31 – Spring 2024