Why armed guards in schools are a bad idea

I just saw this tweet from National Rifle Association (NRA):

Why is the idea of a gun good when it’s used to protect the Pres … but bad when it’s used to protect our children in our schools #NRA

— NRA (@NRA) December 21, 2012

On the assumption that this is a genuine query, I thought I’d take a moment to talk about some simple statistics and probabilities.

First, Wikipedia notes that four presidents (Lincoln, Garfield, McKinley and Kennedy) have been shot by assassins. For simplicity, we will leave aside the failed assassination attempts on thirteen other presidents (and the failed attempts on the lives of Lincoln and Kennedy before the successful ones). Let’s consider the time from Lincoln’s death to now (147 years from 1865 to 2012), and say that the chance of a president being shot dead in any given year is 4 in 147, or about one in 40. (The real chance is surely much higher than that — note that there have been attempts on the lives of all the last eight presidents.)

The population of the US is 315 million, of which 27.3% are under 20 years of age. Let’s assume that about half of those are school age (between 5 and 15), which is 43 million schoolchildren. In 2012, there have been seven notable school shootings, but “only” 29 children murdered as a result. So let’s say that the chance of schoolchild being shot dead in any given year is 29 in 43 million, or about one in 1,500,000.

There were 600 accidental deaths by gunshot in the USA in 2010. Somewhere in the range of 30-34% of adults own a gun. Given that there are 230 million adults in the USA (and assuming that the number of children owning guns is negligible), that means there are about 74 million gun owners in the USA. So the chance of any gun owner accidentally killing someone in a given year is 600 in 74 million, or about one in 123,000.

In reality, of course the armed guards who protect the president are the best of the best: very highly trained, and much less like to have accidents than the general gun-owning population. But even assuming they are no more competent than hypothetical armed school guards, here’s how it works out.

• Giving the president an armed guard increases his chance of being shot, due to accident, by one in 123,000. Given that his chance of being shot is already one in 40, this is negligible.
• Giving children an armed guard increases their chance of being shot, due to accident, by one in 123,000. Given that their chance of being shot was previously one in 15,000,000, it means they are now 122 times as likely to be shot.

These numbers are all approximate. I could easily be wrong by a factor of two or more. Even if I’m wrong by a factor of six, it still means that the president is much, much, much better off with an armed guard where as a schoolchild would be twenty times as likely to be shot.

I hope that clears things up.

Help the USA into the 21st century (even if you’re not American)

[This is cross-posted from my other blog, Sauropod Vertebra Picture of the Week. I never cross-post: this is, as far as I remember, literally the first time I have done it. But this issue is so important and so urgent that I am making an exception. Please, please: sign the petition, upvote the Reddit and Hacker News submissions, blog about it, tweet about it, tell your friends.]

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Good news! If you want to read research that was funded by the U.S. National Instututes of Health (NIH), you can. Their public access policy means that papers published on their dime become universally accessible in PubMed Central.

Can birds fly into a headwind that is faster than their own maximum speed?

I just read this snippet in Gerald L. Wood’s fascinating Guinness Book of Animal Facts and Feats, 3rd edition [amazon.com, amazon.co.uk]:

My plan for 2012: do things that children do

20th January may seem a strange day to make a New Year’s resolution, but it’s not so much a resolution as a gradually growing realisation of what I want out of the year.  Now that I’ve figured it out, I thought I might as well share it here.

When kids are growing up, adults decide what they’re going to do.  And not only do we make better choices for kids than they would make for themselves, we make better choices for them than we do for ourselves.  Here’s what kids do:

• Learn things (in school)
• Play sports (also in school, if not elsewhere)
• Sing and play instruments (e.g. school concerts)
• Draw and paint
• Write stories

(They also play video games and watch TV, but let’s ignore those for now because those are things that adults also do plenty of.)

All those things are fun.  Adults choose them for kids because they know that they’ll enjoy themselves, that they’ll develop their creativity, that they’ll be healthy.  Then having set our kids off on that trajectory, we slump in front of our computers for eight or twelve hours every day.

In 2012, I’m going to do those things, too.  Why should kids have all the fun?

Oppose SOPA, PIPA and the RWA

Today is a big day for the Internet.  Nearly everyone reading this site will be aware of the Stop Online Piracy Act (SOPA) and the Protect IP Act (PIPA), two appallingly ill-conceived pieces of legislation under consideration in the US but with profound ramifications for the whole world.  Written at the behest of big copyright holders by people with no understanding of how the Internet works either mechanically or culturally, they would be absolutely disastrous if passed.

In response to this, many high-profile web-sites are demonstrating the results such laws would have by going dark for the day.  They include Reddit and, most importantly, Wikipedia.  (Also, the entire Cheezburger network and many, many others.)  We can only hope that this distributed demonstration results not just in SOPA and PIPA being rejected, but in an emphatic smackdown that makes it impossible for similarly dumb legislation to get mind-space in the future.

But there is another threat also making its way through the US Congress — less publicised but also hugely important.

It’s gone quiet around here

Folks, sorry for the break in transmission.  I really want to get my review of A Good Man Goes to War done, and foolishly I didn’t feel I should move on to write about anything else before that was done.  But an absolute frenzy at work has meant I’ve not had time to watch it again and write intelligently about it, hence this break.

How to get things done: don’t open your post

This is the pile of unopened post that’s accumulated inside our front door over the last couple of months:

Usually I feel a sort of low-level nagging guilt about this, but actually I think it’s a good thing.

Semantic mapping is hard

A while back, I wrote about the MARC format that is widely used in libraries to represent bibliographic data, and the much simpler Dublin Core set of 15 data elements (creator, title, date, etc.) that can also be used to describe documents — although, as it turns out, inadequately.

There is an official MARC to Dublin Core Crosswalk — i.e. a mapping from MARC elements to correponding Dublin Core elements — developed and maintained by the Library of Congress.  Today I learned, from a CODE4LIB mailing-list message, that the crosswalk does not map any MARC tag to the DC Creator element.  “Creator” is what the Dublin Core set calls the author; so if you have a MARC record describing The Lord of the Rings, and translate it to Dublin Core using LC’s official mapping, the resulting record will not tell you that J. R. R. Tolkien is the author.

Crunchiegate: the cover-up continues!

Dammit, what’s the country coming to?  As though it weren’t bad enough that SSP UK, through their Pumpkin Cafe brand, didn’t give me the 75p cash refund that they promised, it now seems that the “full investigation” that they promised me is being dragged out.  Two weeks after they began this investigation, I haven’t heard a single word from them about it.  You have to suspect a cover-up.

Crunchiegate: full investigation started!

Hot news this morning!  It was late last night that I registered my complaint about not having been issued with a receipt when buying a Crunchie at the Pumpkin Cafe on Platform 9 of Bristol Temple Meads railway station.  But already, in only seven hours, they have emailed me back with exciting news.