From April 2019, the headline prediction covered the Brexit Party and Change UK - The Independent Group. Change UK was later removed from the headline prediction ahead of the 2019 general election as their poll scores were not statistically significant.
The site is based around the employment of scientific techniques on data about Britain's electoral geography, which can be used to calculate the uniform national swing. It takes account of national polls and trends but excludes local issues.
The calculations were initially based on what is termed the Transition Model, which is derived from the additive uniform national swing model. This uses national swings in a proportional manner to predict local effects. The Strong Transition Model was introduced in October 2007, and considers the effects of strong and weak supporters. The models are explained in detail on the web site.
Across the seven general elections from 1992 to 2017:
- EC correctly predicted the party which won the most seats in six out of seven (all except 1992).
- EC correctly predicted the majority party in three (1997, 2001, 2005) and the hung parliament outcome in 2010.
- The mean polling error for the two largest parties was 4.8%.
It was listed by The Guardian in 2004 as one of the "100 most useful websites", being "the best" for predictions. In 2012 it was described by PhD student Chris Prosser at the University of Oxford as "probably the leading vote/seat predictor on the internet". Its detailed predictions for individual seats have been noted by Paul Evans on the localdemocracy.org.uk blog. Academic Nick Anstead noted in his observations from a 2010 Personal Democracy Forum event, that Mick Fealty of Slugger O'Toole considered Electoral Calculus to be "massively improved" in comparison with the swingometer.
With reference to the 2010 United Kingdom general election, it was cited by journalists Andrew Rawnsley and Michael White in The Guardian. John Rentoul in The Independent referred to the site after the election.
- "Electoral Calculus". Intute. Retrieved 17 October 2011.
An independent UK election prediction site maintained by Martin Baxter. He attempts to apply scientific techniques to the electoral geography of Britain to predict the future general election results.
- Ruppert, Evelyn (16 April 2010). "Data mobilisation and the UK 2010 Election". CReSC: The Social Life of Methods. Centre for Research on Socio-Cultural Change. Archived from the original on 10 September 2011. Retrieved 28 May 2012.
- "Scottish Government and Politics on the Internet". School of Politics, International Relations and Philosophy website. Keele University. Retrieved 6 February 2014.
- Young, Toby (7 May 2010). "Who predicted the result correctly?". The Daily Telegraph. Retrieved 25 May 2012.
- "MP's on course to lose his seat". thisiskent.co.uk. Northcliffe Media. 27 April 2012. Archived from the original on 5 May 2013. Retrieved 24 May 2012.
- Baxter, Martin (8 July 2004). "Transition Model". Electoral Calculus. Retrieved 17 October 2011.
- Baxter, Martin (28 October 2007). "Strong Transition Model". Electoral Calculus. Retrieved 17 October 2011.
- Electoral Calculus https://www.electoralcalculus.co.uk/trackrecord.html
- "Cream of the crop". The Guardian. 16 December 2004. Retrieved 28 May 2012.
- Prosser, Chris (7 May 2012). "Predicting the next UK general election". Politics in Spires. Retrieved 25 May 2012.
- Evans, Paul (30 March 2010). "Election websites to watch". localdemocracy.org.uk. Archived from the original on 21 September 2014. Retrieved 25 May 2012.
- Anstead, Nick (15 May 2010). "General Election 2010 – Action Replay (Personal Democracy Forum Event at the Royal Society for the Arts)". nickanstead.com. Retrieved 25 May 2012.
- Rawnsley, Andrew (22 November 2009). "Why it's very likely the next parliament will be doubly hung". The Guardian. London. Retrieved 17 October 2011.
The different formulas used by Electoral Calculus and Swingo both translate a six-point Tory poll lead into a Commons in which the Conservatives are short of a majority.
- White, Michael (30 April 2010). "Tony Blair's back. But it's too late for Labour". The Guardian. London. Retrieved 17 October 2011.
How is Cameron 'winning' when Tory share of the vote is – on current measure – about 1% to 1.5% up on 2005 (source Electoral Calculus)?
- Rentoul, John (17 October 2010). "John Rentoul: Clegg drives his voters away". The Independent. Retrieved 28 May 2012.