Lord Ashcroft's corrected poll paints a very different picture for Ed Miliband. Photo: Getty.
Show Hide image

Ashcroft corrects his Doncaster North poll: Miliband ahead by 29

A weighting error has disproven last week’s headlines – but what happened?

For daily news, polling and predictions, explore our elections site, May2015.com.

Last week, Lord Aschroft created a stir when, in his latest round of constituency polling, he showed Ukip within 12 points of Ed Miliband in Doncaster North. He put the party on 28 per cent, up from 4 per cent in 2010.

But the eagle-eyed Anthony Wells – YouGov's chief political analyst, editor of UK Polling Report, and provider of May2015's historical polling data – spotted an error. The poll was weighted to include too many Tories and too few Labour voters. Ashcroft has always been unerringly impartial in his reporting of his polls, this was a simple data entry error.

The new weightings have put Miliband ahead by 29 per cent, not 12, and give him a higher share of the vote than 2010, rather than a lower one. Our recent, pre-poll suggestion that Miliband could face a battle for his seat now has little support.

The graph below shows how the new poll differs from Ashcroft's previous poll, and the results of the 2010 election.

This wasn't an inconsequential poll. Ashcroft's pre-release tweet was shared on Twitter nearly 600 times.

But how exactly did Ashcroft wrongly weight the poll? There are two steps to creating a representative poll: an initial sampling of the population and then a weighting of them to make sure they are demographically representative (e.g. the correct proportion of age groups, gender, party ID, etc.).

 

The error in Ashcroft's poll was at the weighting stage. His weightings are meant to begin with the 2010 result in Doncaster and make some allowance for the past recall of voters (he asks those he has sampled who they voted for in 2010, which will differ slightly from the actual result). The problem with his first poll was that the past recall numbers for the Tories and Labour were mixed up.

The new weightings are shown below (here are the tables for the first and second poll). As the graphs show, the old weightings implied the Tories won the seat in 2010. The new weightings are close to the 2010 result (past recall accounts for the slight difference), and mean more Labour voters are in the poll.

May2015 is the New Statesman's new elections site. Explore it for data, interviews and ideas on the general election.

Getty
Show Hide image

John McDonnell accuses Labour of “rigged purge” of Corbyn supporters

The shadow chancellor criticises the party's national executive committee for its expulsion of members and supporters from the leadership election.

John McDonnell has accused Labour of targeting Jeremy Corbyn's supporters in a "purge" of those allowed to vote in the leadership election.

"Labour party members will not accept what appears to be a rigged purge of Jeremy Corbyn supporters", the shadow chancellor wrote. "The conduct of this election must be fair and even-handed."

McDonnell, who is Corbyn's campaign manager, added: "I am writing to Labour's general secretary Iain McNicol to demand that members and supporters who are suspended or lose their voting rights are given clear information about why action has been taken and a timely opportunity to challenge the decision. In particular, the specification of particular terms of abuse to exclude Labour party members from voting should not be applied retrospectively."

The statement follows the suspension of Bakers' Union boss Ronnie Draper from voting in the election, an action Draper attributed to unspecified previous social media posts. Labour's national executive committee has not commented on the reasons for his suspension.

"While Ronnie, a supporter of Jeremy Corbyn, has been denied his say in Labour's elecion, no action is being taken over the Labour peer, Lord Sainsbury, who has given more than £2m to support the Liberal Democrats," McDonnell said. "And no action has been taken against Michael Foster, the Labour party member who abused Jeremy Corbyn's supporters and staff as Nazi stormtroopers in the Daily Mail."

McDonnell's statement adds to an already febrile mood over the election, which sees Corbyn pitted against challenger Owen Smith. A week ago, a group of Labour grandees signed a letter condemning "intolerable" attacks on party staff - who are not allowed to respond to allegations made against them. The latest statement will be seen as a warning shot to general secretary Iain McNicol, who the leadership feel has consistently interpreted the party's rules to Corbyn's disadvantage. 

Helen Lewis is deputy editor of the New Statesman. She has presented BBC Radio 4’s Week in Westminster and is a regular panellist on BBC1’s Sunday Politics.