I got myself in a debate on Twitter last night about this question. Someone made the following statement about people in Scotland

the majority wants Trident out.

I responded

Scot Soc Att Survey – 59% either in favour of nuclear weapons or no view

To ‘fess up straight away I was wrong about 59%, the true figure is 53%, but that’s still a majority. I gave a link to the correct data online (it’s set out in detail below) and the full source is the excellent Scottish Social Attitudes Survey.

What happened next is worthy of some examination because there is a view around the independence referendum that people don’t have enough information available to decide. This particular exercise in correcting one small misapprehension led to the following exchange

HIM: nice manipulation of the data. Kudos

ME: Since I gave rational answer to yr prev point I assume ‘nice manip’n of the data’ isn’t directed at me

HIM: no you attempted to manipulate data to substantiate your opinion.

HIM: it isn’t a factual error…Out of those that have an opinion, the majority want it out

ME: Have to agree to differ then because I think ‘neither in favour or against’ *is* an opinion

HIM: not when you’re claiming majority by manipulating stats. Majority of those of opinion want it out

HIM: is that correct? yes or no?

ME: I can’t explain further but I do have a reasonable understanding of statistics. Good night.

So without the constraints of 140 characters per message of Twitter who’s right, ‘him’ or ‘me’?

Here are the statistics I was referring to, courtesy of ScotCen Social Research:

Trident table

Click to enlarge

Source: Table in Scottish Social Attitudes Survey 2013

The first thing to say is the question asks whether Britain should have nuclear weapons, not Trident specifically. But since Trident missiles are the only nuclear weapons Britain possesses it’s a reasonable approximation. It should also be noted that the Scottish Social Attitudes Survey is a reputable, reliable and statistically valid source of opinion on the subject matter it covers. I know of no other up to date neutral source that addresses the same issue.

The nub of the difference between my interlocutor and me is whether people who answered ‘neither in favour or against’ should be included in the calculation of the percentage of people ‘against Trident.’ I say yes because to be neither for nor against is to express a view. Moreover, even a survey of this high quality is a relatively blunt instrument at catching the full subtlety of people’s opinions. So I could easily imagine a whole range of views underlying an opinion that someone is neither in favour nor against Britain having its own nuclear weapons. For example

  • You know, I couldn’t care less. I’ve got more important things to worry about
  • Well, I can see things for and against. It’s a fine balance
  • It’s not really relevant to defence these days but if the experts want it…
  • and so on.

In any event, the statement originally made was that ‘the majority wants Trident out’, not ‘the majority excluding “don’t knows” and those “neither in favour nor against” want Trident out’ – as the other person concerned amended his claim to when challenged. These are two quite different things.

To put it another way, if you lined up 100 Scots and said ‘Will everyone who is somewhat or strongly against Britain having nuclear weapons please step forward?’ 46 would. That’s a minority.

This sort of detail is important because it’s the only way to tease out the claims and counter-claims that accompany the independence referendum debate.

Incidentally, the question of Scotland being different from the rest of the UK features prominently in ‘Yes’ claims about the independence referendum. It is interesting to compare the results of the same question asked in the Scottish Social Attitudes Survey’s sister survey south of the border (the small percentages of ‘Don’t know’s have been excluded from this table).

Trident UK

As the authors of this comparison say

The differences in the level of support are not that large, and both parts of the UK could reasonably be described as being divided on the subject (the full report can be downloaded here).

To go back to the original issue, I maintain that there is not a proven majority of people in Scotland who ‘want Trident out.’ But I’m open to reasoned arguments that prove the opposite.

 

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Great headline in my local paper today, the esteemed Aberdeen Press and Journal:

Study shows risk of dying doubles.

So that would be doubled from 100% would it?

The text of the article compounds the error:

Scientists in the US found that “feeling lonely” almost doubled the risk of dying in a population of 1,600 older individuals.

Of course, what it really means is that at any given age loneliness can almost double the risk of dying.  At the end of the day the grim reaper gets us all.

It reminded me of a diagnosis I once had of a (not actually too serious) medical problem.  The first medic, a rather gloomy registrar volunteered ‘You have an irreversible degenerative disease, Mr White.’  When I retailed this to the head honcho, a neurologist, he added the helpful corrective – ‘Yes. We all have an irreversible degenerative disease.  It’s called life.  And what’s more it’s sexually transmitted.’


Yesterday in what turns out to be Round 1 of this subject I wrote

[MP Nadine] Dorries … said that we… have “more abortions than anywhere else in Western Europe”…   I have neither the time nor the will to delve into this generalisation.

Somehow, overnight I summonsed the will to look at the data and again the truth turns out to be more complex than the politician’s easy generalisation:

Italics – most recent year available if not 2008

Source: Eurostat databases

As with all statistical data the devil is in the detail.  Ms Dorries talked about “Western Europe” and in the absence of an official definition I have used my own.  For one reason or another there is no data available for Ireland, Greece, Luxembourg, Netherlands, Austria or Portugal.

When commenting on her other claims on this subject I used figures for England and Wales as these are the headline numbers the Department of Health publish.  Scotland and Northern Ireland have devolved responsibility for health.  Strictly speaking I should also have excluded Welsh data for the same reason, which would have brought Ms Dorries’ claimed “200,000” abortions per year down to just under 181,000 in 2010.  This seems reasonable because the changes to the abortion law she seeks would only apply to England.  On the other hand, when making international comparisons, the only data available is at UK level, and only for 2008.

Having said all that, we can return to Ms Dorries’ claims and conclude

  • Yes, we did have the highest number of abortions in Western Europe, but only in 2008 (since when our figures have fallen slightly – data is not yet available for other countries) and only slightly more than France
  • However, on the much more meaningful measure of the chance of a woman having an abortion (the rate) France and the UK are virtually the same and have the second highest rate in Western Europe
  • The highest rate of abortions in Western Europe, considerably higher than either the UK or France, is in Sweden
  • There is arguably a cluster of four countries –the UK, France, Norway and Denmark – where the rates of abortion are not that different.

So the scary headline the highest number of abortions, with all its negative connotations, turns out to tell only part of a complex story.


I don’t have the figures in front of me but I can guarantee to you that 15 years ago the incidence of abortions was far far fewer than it is today.  Today we have 200,000 abortions carried out per year…I think 15 years ago the figure may have been around 40,000 per year – Nadine Dorries MP on BBC Radio 4’s World at One Programme 29 August 2011

Sometimes I despair at how some politicians use statistics.

The quote above is a classic example.  Here are the true facts:

  • No. abortions in England and Wales in 1996 – 167,916
  • No. abortions in England and Wales fifteen years later in 2010 – 189,574

It’s easy to get a number wrong.  But by a factor of over 4 (the 1996 number)?  Frankly it’s unbelievable.

My figures come from the Department of Health’s publication Abortion Statistics, England and Wales: 2010, as up to date and accurate a set of statistics on the subject as I could find.

Perhaps Ms Dorries didn’t find them.  Perhaps she found them and mis-read them.  Perhaps she forgot the detail in the heat of the moment.  Perhaps she has an alternative and more accurate source of data the rest of the world hasn’t heard about.  Perhaps, heaven forefend,  she was guilty of mis-representation.  Perhaps she was talking through…don’t even go there.

Here’s a more factual although less exciting look at the statistics.

First, the simple number of abortions each year:

Now the rate of abortions – to allow for the difference in the number of women aged 15-44 over time:

It’s quite a different picture isn’t it?  Here’s my take on the figures:

  • The number was much higher fifteen years ago than Ms Dorries claims, therefore any increase since then is much less than she implies
  • The number now is not 200,000, it is just under 189,600 – or 5% less than the claimed figure
  • Both the number and rate of abortions have tended to go up and down together
  • There has actually been a decline in the number and rate of abortions since 2006
  • When you look at the rates they have not varied that dramatically – from 15.7 per thousand women in 1996 to 17.9 in 2007 and 17.1 in 2010
  • If 1.71% of women had an abortion in 2010 (17.1 in 1,000) then 98.29% didn’t.

Ms Dorries also said that we (England and Wales, Britain, the UK?) have “more abortions than anywhere else in Western Europe”.  The latest Eurostat publication on the subject shows she may be on slightly firmer ground here but her statement takes no account of the relative size of each country.  I have neither the time nor the will to delve into this generalisation. [But I changed my mind overnight – see my post Politicians and statistics Round 2]

It’s not so long ago the Labour government couldn’t utter the word “policy” without preceding it with the adjective “evidence-based” and it’s still a phrase many politicians reach for to justify what they want to do anyhow.  A key part of Ms Dorries’ evidence base for her belief that abortion should be more restricted would appear to be dodgy at best, completely fallacious at worst.

Readers should not infer from this post that I have any particular point of view on the subject of abortion .  My interest is in the use and abuse of statistics and some of you will know that one of the services HelpGov offers is helping establish the facts.