Last month Chris Elliot, the Guardian’s readers’ editor, quoted a letter from a reader saying there “seemed to be a cultural problem among Guardian reporters that it is of no consequence if you completely misunderstand or mis-report the figures in a story [...] I hope that you can urge on the editor some training of reporters on basic understanding of statistics”. Chris Elliott said he had organised three sessions with external statistical experts for Guardian journalists in the past year (and Nigel Hawkes at Straight Statistics reveals he was one of them).

The Observer’s readers editor should probably do the same. Earlier this month the Guardian’s front page story mentioned an open-access voodoo poll on the Royal Medical Journal’s website that had been touted round Twitter as if it was meaningful. The Observer this weekend was on a similar subject, but was worse – hanging a whole story on very dubious figures.

The story is titled “Nine out of 10 members of Royal College of Physicians oppose NHS bill”, and claims that “a new poll reveals that nine out of ten members of the Royal College of Physicians – hospital doctors – want the NHS shake-up to be scrapped.”

The story is based upon an open access survey created by and linked from a website campaigning against the heath bill, callonyourcollege.blogspot.com, and again, bandied around Twitter. The survey was open access, so there could have been no attempt at proper sampling and contained no demographic information that could have been used to weight it. It should go without saying that a survey from a website campaigning against the NHS reforms and co-ordinating opposition to it amongst the Medical Royal Colleges is more likely to be found and completed by opposed to the bill (in much the same way that a poll carried out on, say, the Conservative party’s website, might be considerably more supportive).

Any poll actually measuring the opinion of members of the RCP would have needed to randomly sample members, or at least contact members in a way that would not have introduced any skew in those likely to reply. For all we know this may have also shown overwhelming opposition – but we cannot judge that from an open-access survey liable to have obtained an extremely biased sample.

Once again, I would urge any journalist thinking of including any polling figures in a story to look at this guidance from the British Polling Council, particularly on how to judge whether to take a poll seriously or not. If these had been looked at, the Observer should never have got to this point…

Who conducted the poll? Was it a reputatle, independent polling company? If not, then regard its findings with caution

In this case, the poll was not conducted by a polling company, but by a group lobbying against the bill they were asking about. This should have been the first alarm bell.

How many people were interviewed for the survey? The more people, the better — although a small-sample scientific survey is ALWAYS better than a large-sample self-selecting survey.

In this case, the number of people interviewed is not mentioned. It could be high, it could be low. But note Peter’s other point… this was a self-selecting survey anyway…

How were those people chosen? If the poll purports to be of the public as a whole (or a significant group of the public), has the polling company employed one of the methods outlined in points 2,3 and 4 above? If the poll was self-selecting — such as readers of a newspaper or magazine, or television viewers writing, telephoning, emailing or texting in — then it should NEVER be presented as a representative survey.

This was a self-selecting poll of doctors directed there from a site campaigning against the legislation. There is no way it should have been presented as a representative survey.

UPDATE: Credit where it is due. Denis Campbell, one of the authors of the piece, wrote about the same poll on the Guardian’s rolling blog the next day, but this time caveated it with “But that was to a website run by anti-Bill doctors and a self-selecting rather than scientific poll, so may not reflect opinion precisely.” In a perfect world I’d hope that journalists would spurn non-representative polls completely, but progress nonetheless.

The Press Association are reporting that “The majority of people from across the political spectrum believe Scotland should be responsible for raising most of the money it spends, according to research from an independent think-tank.”

Because it is on the Press Association feed, this is then repeated verbatim by various other newspaper websites here, here, here, etc, etc, all labouring under the misapprehension that because the Press Association reports a poll it is meaningful. They are wrong.

The “poll” was conducted by Reform Scotland, a think tank that published proposals for devolution plus earlier this year. The “sample” was drawn from people on Reform Scotland’s mailing list or following them on twitter. Needless to say, this is not a method likely to provide a representative sample of the Scottish public as a whole.

I hate to write as if addressing morons, but sadly it sometimes appears as if it is necessary. People who have signed up to follow a think tank that has proposed a devolution plus plan are, firstly, far more likely to be interested in politics (the vast majority of normal people are not on the distribution lists for think tanks!) and secondly, likely to be pre-disposed towards further devolution of power towards Scotland (for what it’s worth, the poll is also three-quarters male, only 10% over 65+ and has more Tory identifiers than Labour ones).

To give them some credit, Reform Scotland themselves haven’t claimed it is a representative poll, saying “We do not claim that this poll is totally scientific as it was self selecting. However, the responses, particularly those broken down by party affiliation, are very interesting, in particular”. Alas, the reality is that these caveats never get picked up by journalists, and such surveys inevitably end up being misreported as representative meaningful polls. For the record, the party breakdowns are not of any meaning either, since in the same way the poll overall will be grossly biased towards people with an interest in Scottish politics and a predisposition towards greater devolution, so will each of the party crossbreaks (i.e. the Labour voters in the sample will be more political and more in favour of further devolution than the average Labour voter, ditto other parties. They are also grossly demographically skewed towards younger men, and apart from the SNP have sample sizes under 100).

Over on the British Polling Council’s website there is an article written by Peter Kellner several years ago titled “A Journalist’s Guide To Opinion Polls”. Amongst other things, it gives guidance to journalists on when to take a poll seriously, and when to bin it. It is still flawless advice today:

“If the poll purports to be of the public as a whole (or a significant group of the public), has the polling company employed one of the methods outlined in points 2,3 and 4 above [quasi-random or quota sampling]? If the poll was self-selecting — such as readers of a newspaper or magazine, or television viewers writing, telephoning, emailing or texting in — then it should NEVER be presented as a representative survey.