Election forecasting

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

August 4, 2024 By Nigel

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.

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

July 3, 2024 By Nigel

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.

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

June 30, 2024 By Nigel

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.

UK General Election 2024 #3 – My Forecast as of 23rd June 2024

June 23, 2024 By Nigel

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

CON 108
LAB 442
OTH 100

UK General Election 2024 #2 – My Forecasting Model

June 22, 2024 By Nigel

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.

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

June 8, 2024 By Nigel

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.

Voice Referendum #2 – My Forecast Reviewed

November 5, 2023 By Nigel

Australians rejected the proposed constitutional amendment known as The Voice in a referendum on 14^th October 2023. NO won the national vote by 20.1 percentage points and the state count 6-0 but the more important question is was my forecast right?

Voice Referendum #1 – My Forecast Explained

October 13, 2023 By Nigel

Australians will reject the proposed constitutional amendment known as The Voice in a referendum on 14^th October 2023. My forecast is for NO to win the national vote by 17 percentage points and win the state count 6-0.

This article was first published on 11th October 2023. My forecast then was for NO to win 16 points and the state count 6-0.

UK General Elections #5 – How accurate are voting intention polls? – updated with GE19

December 29, 2019 By Nigel

After 3 general elections with severe polling errors, the UK opinion pollsters redeemed themselves in the 2019 UK General Election with their most accurate performance since 1955. I base this statement on data provided by Mark Pack who has systematically recorded every opinion poll published since 1945. The challenge now for the industry is to maintain this level of performance for the next election which may be easier said than done given that 5 out of the last 8 elections have experienced a major polling error.

UK General Election 2019 #2 – My forecast is the most accurate & beats the Exit Poll!

December 16, 2019 By Nigel

At 2200 on Thursday 12th December 2019, the BBC/ITV/Sky Exit Poll was revealed to the nation and pointed to a large majority for the Conservatives. Unlike 2017, I was able to turn to my wife and say “it looks like I will be right this time!” By the end of the night, Gavin Freeguard from the Institute of Government was tweeting that not only was I the most accurate election forecaster of 2019, I was more accurate than the Exit Poll.