Lib Dem private polling
The Lib Dems have been out and about briefing journalists about what their polling shows. This morning the Guardian, May 2015 and The Spectator have all written about it.
Private polling always has a certain allure when spoken of in the media, there is that whiff of forbidden, insider knowledge. It really shouldn't - beyond asking whether such private polling actually exists, the first major caveat to any claims that private polling shows something different to publicly available stuff is "why should it?". Political polling doesn't really make much money, it's normally done as a shop window to get a polling company's name known and to create a reputation for accurate research. It is in polling companies' interest for their voting intention polls to be as accurate as possible, so the publicly available stuff really is the best we can do, there is no more accurate version of the data held back for private clients. Therefore, most of the time when political parties claim their private polling shows them doing better than the public polls it suggests they are making it up, or they have been commissioning stuff that asks things in a skewed way for propaganda purposes (what Lord Ashcroft has called in the past "comfort polling").
Even if the full details of private polls are released, with all the methodology and tables available for scrutiny, you should still view them sceptically.
Parties decide which polls to release or brief journalists on, if any. One thing you never see is a political party releasing a poll that is not helpful to them, so even if the polling itself is above board, there is a strong publication bias; only the stuff that helps the party is published.
To illustrate that, cast your mind back to the polling of Lib Dem seats conducted by Lord Ashcroft. One of the most obvious findings was how much the Lib Dem performance varied - in some seats like Eastborne, Birmingham Yardley or Sutton & Cheam the party is doing very well indeed. In other seats like Somerton and Frome, Chippenham and Brent Central they are doing atrociously. Imagine the very different narratives that could be created by selectively releasing polls from those first three seats, as opposed to selectively releasing polls from the latter three.
So what should we make of the Liberal Democrat claims? Well, the polling does genuinely exist - Survation are a proper company and while the newspaper reports don't include specifics, several journalists have assured me they were shown the actual figures. For once, there is also a legitimate reason why the Liberal Democrat polling might show them in a better position than the published polling - the articles suggest they prompted using candidate names. We know that a lot of Lib Dem support is reliant upon tactical voting and personal votes, so it seems reasonable that polls that include the candidate names in Lib Dem held seats might show the Lib Dems doing better. Until we see tables we can't tell what other methodological factors may have been at play.
The articles claim that the Lib Dems have done about 100 constituency polls, while it seems journalists were shown results from about a dozen or so, so it is impossible to know how representative this group were, or whether they were cherry-picked to create a good impression of the Lib Dem performance.
Even if you take the claims that the Liberal Democrats make at face value, they don't actually show much that contrasts with existing publically available data that much. According to the Guardian the party "is on course to remain "competitive" in seats that would fall if there was landslide against the Lib Dems, such as Cheltenham, St Ives, Cardiff Central, Eastbourne, Solihull, Cheadle, Leeds North West, Cambridge and Bermondsey." From talking to several other journalists who were there, I'm told they were also shown figures from St Austell and some other Labour facing seats, so perhaps a dozen in total.
The word "competitive is vague" - it could mean both a little ahead... or a little behind. As it happens, Lord Ashcroft has conducted polls in nine of those seats, and in most of them the Lib Dems are indeed "competitive". In three of them (Cheltenham, Cheadle, Eastborne) Ashcroft found clear Lib Dem leads, in two others (Bermondsey and St Ives) he found the Lib Dems just ahead (though I'm told the Lib Dem polling shows them doing better than that). In Cambridge Lord Ashcroft he found them a point behind... but that counts as "competitive" in my book. The other three are St Austell & Newquay, Solihull and Cardiff Central, where Ashcroft found the Lib Dems trailing. If the Lib Dem data was kosher, then it may well show the Lib Dems doing better in those seats... but polls vary, and perhaps there are other, unmentioned, polls that show the Lib Dems doing worse than in Ashcroft's polling.
