Trying to make sense of nonsense

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Have yourself a merry epi-Christmas: gift ideas for epidemiologists (and possibly a few statisticians)

With only a couple of days left until presents are expected to magically appear under trees, here are a few (affordable) suggestions for gifts for that special epidemiologist in your life.

Naturally, you could get him/her a John Snow mug (though beware true coffee/tea addicts: the mug is a bit on the small side), Florence Nightingale, or a brain-eating amoeba, or perhaps a cuddly, but evil Poisson distribution (oh, it promises to be discreet, but as soon as you say something negative it bails on you). There’s even some stuff if you want to be more traditional and go with jewellery: a π necklace for instance, or a necklace spelling out ‘I am star stuff’ in amino acids (the shop is closed at the moment unfortunately).  And best of all, there’s the Sciencegrrl  calendar – and tote bag, badges and memory sticks – which is pretty awesome and features epidemiology girl Soozaphone as April.

Evil Poisson distribution, conniving its evil plans to discreetly take over the world of distributions

But hey, if you’re anything like me, you’re planning to spend the entire Christmas break reading on your parents’ couch, so here are my favourite three 2012 books vaguely related to epidemiology:

3. Ben Goldacre: Bad Pharma
A good book on an important topic, that happens to partially coincide with my PhD, so I’m probably a bit biased. It’s not a book to read in one go, if only because your blood will boil, and as the trials on blood pressure drugs are a bit dodgy, that might not be a good thing.
The title of the book might be a tad bit misleading though as Big Pharma isn’t inherently bad, we (regulators, academics, governments, patient groups, the public) just let them get away with it. Google, Amazon and Starbucks are ‘morally wrong’ in trying to pay the least possible amount of tax, but we don’t put the sole blame on them. The same principle goes for Big Pharma: we let them do it. Let’s change that.
So why only third place? Well, there happened to be two even more awesome books vaguely related to epidemiology published this year (that, and I can’t figure out the braille joke on the cover, which has been bugging me for weeks).

2. Jon Ronson: The Psychopath Test
A mystery package from Sweden arrives in an academic’s pigeonhole in London. There is no return address. Inside the package is a book of which every other page is blank, the pages with words on them have words cut out, and it is written by a ‘Joe K’. Intrigue follows: many academics all over the world, in distant corners such as Tibet and Iran, have received the exact same package. The London academic decides to enlist Jon Ronson to find out what’s going on and a journey into the madness industry follows.

The book might be a particularly good read with DSM-5 coming up in 2013. Psychology Today has a nice overview of everything that might be wrong with this new edition of the ‘bible of mental health disorders’ (calling it that for one). Perhaps everything will be all right and the new DSM will just create more psychiatric atheism among those wielding the power to diagnose, but with normal behaviour such as grieving longer than two weeks being classed as a mental disorder,

1. David Quammen: Spillover

@david_dobbs’ copy. Mine pretty much looks to the same though less colourful as I just dog eared the whole book

“If you look at the world from the point of view of a hungry virus, or even a bacterium – we offer a magnificent feeding ground with all our billions of human bodies, where, in the very recent past, there were only half as many people. In some 25 or 27 years, we have doubled in number. A marvellous target for any organism that can adapt itself to invading us.” William H. McNeill – historian

I’ve grown up in a part of the world that was hit by epidemics almost every other year, or so it seemed at the time. It was horrible. Going to school every morning and not knowing who would be victimised next. Luckily, they weren’t epidemics affecting humans, but livestock. We had classical swine fever in 1997/98, foot-and-mouth disease in 2001, and blue tongue in 2006/07. During those epidemics, the farms of my school friends would be hit one by one. They had to stand by as professionals came in to kill off thousands of animals which they loved and were their families’ only source of income. Later that same day it would all be repeated on the TV during the eight o’clock news, and the next day the trucks would pull up at their neighbours’. It was hard. And it became even harder after 2007, when it turned out that one of those epidemics, Q-fever, was affecting humans.
When we think about where the Next Big One might come from, a rural village in the Netherlands doesn’t tend to be high on the list. Nevertheless, it features in ‘Spillover’ as one of the places where a spillover, the transmission of an infectious disease from animal to human, happened recently. The Dutch story might not be as thrilling as capturing bats potentially infected with a deadly virus (Marburg), tailing gorillas who could be the host of the elusive Ebola virus or tracking down stories on the origins of SARS, HIV and Nipah. The latter, though relatively unknown, caused an outbreak in Malaysia when it spread from fruit bats, via pigs to humans. A million pigs had to be killed. “There’s no easy way to kill a million pigs,” notes Dr Hume Field, one of the experts followed by David Quammen in the book. Later he corrects himself: It was in fact 1.1 million pigs. The difference might seem like just a rounding error, he tells Quammen, but if you ever had to kill an “extra” hundred thousand pigs and dispose of their bodies in bulldozed pits, you’d remember the difference as significant.
Spillover is, without doubt, the most intriguing book I’ve read all year.

A Sciencegrrl Christmas!

A Sciencegrrl Christmas!

*But perfectly timed for my birthday in January 😉


Stata: it’s what the cool kids use

You might have it somewhere already, but in just a couple of weeks, the year of statistics will start. I expect there will be lots of posts on this sexy science, featuring references to bikinis, the exciting things they and statistics are supposed to hide, so you might as well get in on the action early. One thing we statistically-minded people all love, is our statistical software package. It’s a bit like browser preference, where you try to tell someone’s competence by the package or browser they use. SPSS is the internet explorer equivalent for instance, while Stata, R and SAS would be Firefox (add-ons and a new update every week), Chrome (free, but you can’t see what’s going on), and SAS (the fancy industry people use it most), respectively.


My favourite is Stata, and for a very simple reason: someone wrote a program to play hangman with it (and perhaps also a bit because of the Statasaur t-shirt pictures above). Unfortunately for us epidemiologists, Marek Hlavac (the creator of Stata hangman) is an economist, meaning that the words to be guessed are not very epidemiology or statistics-based. So I made an epi add-on.

Or rather, I started on one as I found out I don’t know that many famous statisticians (though Wikipedia helped) or epidemiologists. Moreover, there are scarcely any women I included: I was a bit hesitant about including anyone still alive (with some notable exceptions though), so I didn’t get much further than Florence Nightingale and Ada Lovelace (as there would be no Stata without computers). But as Ada Lovelace day is coming up next week (16th October everyone!), I thought this might be a nice time to try to find out about all the female epidemiologists and statisticians out there.

I haven’t added too many myself, as I didn’t just wanted to add anyone I know of: it might get to the point where names are just impossible to guess in the game. At the same time: it might just be the thing to do as you’d learn about lots of epi-women (maybe I’ll adapt the program to include a google command so you can find out about all these women immediately!)

To try out stata hangman, you can download the original do-file (which contains the programming for the game) and the .dta file (containing the words-to-guess) from this website.

As I don’t think I can upload .dta files on WordPress: here is an excel file of the epi-addon: hangman_epi_addon (.xlsx file)

To import it into stata and save it as a .dta file:

import excel "path_where_you_saved_it\hangman_epi_addon.xlsx", sheet("Sheet1") firstrow allstring clear
save "path_where_hangman_do-file_is_saved\hangman_epi_addon.dta", replace

But more importantly: who else  should be included on the list?

Edit: found the Wikipedia-epidemiologists list and added a lot more epi-women!

How to publish a paper: a student’s perspective (part 1)

With only 3 papers with my name on it, I’m definitely not an expert when it comes to getting papers published. However, those 3 papers (and one that’s waiting in some reviewers’ inboxes right now) have been rejected a total number of 12 times, giving me at least some experience in preparing and submitting them. Maybe that’s why I got invited to give a talk on publishing papers at the student skills workshop at the ICPE – the International Conference on Pharmacoepidemiology and Risk Management. Or it might have been that when a publisher dropped out last minute, and the organisers (one of whom I happen to share a supervisor with) really needed someone who had already booked their tickets to Barcelona.

Either way, I’ve got a presentation to prepare for, and in doing so, I’ve found that actually I have developed a bit of a five-step system when it comes to preparing papers. Even more so: when talking with other students and staff around my department, I’ve found some interesting tips and thoughts on how to get published. I felt it might be worth it to actually write all of this up in a blog (and get some last minute considerations to add to my talk?), as a reference to build on, so here we go:

Step 1: Selecting a journal

Nature vs. Science - Comic by PhD Comics

I’ll start at the point where you’ve done all your analyses and have pretty good idea what you want your paper to be about. Maybe you’re working on that first draft, or you’re already on version 17.3, but at some point you’ll have to start considering what journal to submit to. As my first supervisor told me when my very first paper was rejected by JAMA: “If the first journal you submit your paper to accepts it, you didn’t aim high enough”.

And there you immediately have your first problem: what constitutes aiming high? Impact factors are one determinant of ‘high’, though we all know now that using those in any decision making will only prove you are statistically illiterate. Rather, you could aim at submitting to one of the general medicine journals, such as the New England Journal of Medicine, JAMA, the Lancet or BMJ. All of those boast large regular reader counts and even larger rejection rates.

The scopes of these journals are wide, but they will only consider the studies that will keep their impact factors up, so it might be good to consider some more specialist journals as well. You might not reach as many researchers, but you are more likely to reach the right ones. To find out which are best for your research, go over the papers your citing: there are bound to be some relevant journals there. Or ask an expert; you’re collaborators (if you have any) will probably be able to make some suggestions.

These can ideas can then form a list of potential journals to submit to. Being rejected becomes a lot less painful if you’ve your plan B at the ready. Final considerations will depend on your funder (should the journal be open access?) and funding (yes, it costs money to be published).

Step 2: Formatting and editing

However much I’d like it, there is no getting out of formatting or weeding through formatting guidelines (at least not until you’re senior enough to have someone do it for you), but there are some little things that can make it easier. One of these is Wordle, which creates a ‘word cloud’ highlighting the words you’ve used most often. The first time I copied a paper of mine in there (luckily just before I meant to send it to my supervisors), one word stood out like a sore thumb: However. Without really noticing it, I had started using the word in every other sentence in the discussion. Apart from highlighting unnecessary repetitions, it’s also a very nice tool for identifying key words in your paper: if the right ones don’t come up, you’re probably using to many different terms to describe one phenomenon.

Also important: use a reference manager (I like Zotero – it’s free and integrates with Firefox/Chrome, so you can you use it on any computer without needing to bring the most recent database file with you). Different programs will have different (dis)advantages, so shop around a bit before you decide upon one, there are a lot of options out there.

Draft approved - comic by PhD Comics

Another tip is to read your paper aloud. After taking six years of Latin, I’ve really come to love subordinate clauses and the dactylic hexameter. Unfortunately, they don’t work so well for academic writing, and reading sections aloud really helps in locating the overly complicated sentences I can come up when left to myself for too long (enter joke about ablative absolutes). It works even better when you leave your paper for a few days or even weeks, and then come back to it. Instead of reading what you think is there, you’ll suddenly be able to see what it is actually there.

When you finally come round to sending it to your co-authors make sure you give them enough time. Or even better: decide on a revision plan. How many times will each co-author see the paper, and in which order will you send it round? It can be hugely ineffective to send it to everyone at the same time, as you will end up with lots of similar or contradictory comments. Of course this will get more difficult with increasing numbers of co-authors, but it is important to keep at least the PI and supervisors involved.

One last formatting tip: LaTeX. It’s amazing. Like reference managers format your references, LaTeX can format your entire paper. It will take a bit coding (unless you opt for a program like LyX – thank you @JStreetley), but it will be worth it. One downside: the resulting text will be in PDF, making it harder for some reviewers to write comments or make changes.

Naturally, publishing involves a lot of waiting. So as my post is already past the 1,000 word mark, I’ll leave you to wait for part 2 (submitting & final checks, results!, and responding to reviewers’ comments) tomorrow.

Live below the line day 1: that CAN do attitude

Inequality and deprivation are some of the most important problems in the world today. They limit access to health care, create a whole range of specific health care problems and can even limit the lifespan of people living a civilised, developed city as London. As Sir Michael Marmot famously pointed out: from Westminster to Canning Town, separated by just 8 stops on the Jubilee line, the average life expectancy drops by 6 years.

To demonstrate the problem in a more concrete way, I’m participating in Live Below the Line this week. I’m living of £1 a day, the UK equivalent of the extreme poverty, something which 1.4 billion people on this planet have to every day. Also, to try and make the world a tiny bit better, I’m trying to raise money for Positive Women, a charity set up to empower women and children in Swaziland. You can support them via my sponsor page.

And now for my discoveries on my first day of living on £1: you really need that can do attitude. And I mean that quite literally: all I could afford for my £1 were cans.

Cans. And instant noodles (£0.11!!)

Fresh vegetables and fruit are definitely off the table for the week. As is meat, but as a vegan I’m pretty much okay with that. I’ve tried to bulk buy stuff for the whole week, and have managed to keep spendings within budget so far. I shall see how I fare the rest of the week.

Live below the line day 1: bulk buying

I’ll try and blog about problems I run into this week, and introduce an occasional begging slot to make my goal of raising £100 for Positive Women (Please donate! Even if it’s just £1!). See you on the other side!

Myths about moms: can they ‘have it all’?


The overreaching working mom: a concept as outdated as the corded phone

With International Women’s Day on the 8th, Mothers day on the 18th (if you are in the UK at least) and Women’s History Month for the entire duration of March, women have been the focus of a lot of news stories. A lot of these are positive, inspiring stories, others perhaps a bit unsettling, and others are stories we have heard many times before.

In that last category, working mothers are a favourite. News article reporting on the continuous stress of being a working mom, or the detrimental effects working moms have on their children’s development are plentiful. Most of these stories are based on a single, often misinterpreted study, or try to claim that it is common sense that children need their mothers to be bodily present in order for them to grow up normally. But do these claims hold up when we look at actual data?

In recognition of International Women’s Day, UCL dedicated one of its famous lunch hour lectures to the topic of working mothers (available to watch online here). Dr Anne McMunn elaborated on her research tracking mothers and children over time using two birth cohorts: one from 1958 whose children have grown up to be the working mothers of a generation, and the Millennium Cohort Study, whose children are under the auspices of working mothers today.

You might be forgiven for thinking that working mothers are a stressed out bunch. A quick Google Image search brings up plenty of pictures of multitasking moms faced with demanding toddlers, dishes, dodgy suitcases and corded phones. Meanwhile, a similar search on workings dads brings up an entirely different array of pictures (although the one does show a challenging combination of paternal multitasking).

Most of us seem to agree that the idea that it is impossible to combine motherhood with a career is as dated as the corded phones accompanying most articles on the subject. The second myth, that children are the ones who suffer from not having a stay-at-home mom, appears harder to beat.

It is obvious that having a working mom, as a breadwinner or as second working parent, has its benefits: she serves as a role model, and the extra cash a second working parent can bring in would certainly not be missed in times like these. The question is whether these benefits weigh up to the drawback of having less parent-child face time.

According to research by Dr McMunn, the benefits of being a working mom clearly outweigh the risks(1). Her team looked into the socio-emotional behaviour of just under 13,000 five-year old children in the Millennium Cohort Study. They compared children growing up in a dual-earner household, with those in other types of household, such as traditional household, households with a female breadwinner, unemployed households and lone mothers.

The socio-emotional behaviour the researchers were on the lookout for included behaviour such as hyperactivity and emotional symptoms. These behaviours would be the sort of problems you might expect if children really were at a disadvantage from having their moms go to work. When they compared the number of children displaying these sorts of behaviours between family types, taking other factors such as mother’s age, education, possible depression and household income into account, it became apparent that children of dual-earner parents were quite well off.

Even more so: the most beneficial working arrangement for both girls and boys was that in which both mothers and fathers were present in the household and in paid work. These results add to a growing body of work showing that having a mother with a paid job can only be a good thing (see for example: 2,3). The idea that having a working mom is bad for children appears to no more than a myth.

1.         McMunn A, Kelly Y, Cable N, Bartley M. Maternal employment and child socio-emotional behaviour in the UK: longitudinal evidence from the UK Millennium Cohort Study. J Epidemiol Community Health. 2011 Jan 10.

2.         Cooksey E, Joshi H, Verropoulou G. Does mothers’ employment affect children’s development? Evidence from the children of the British 1970 Birth Cohort and the American NLSY79. Longitudinal and Life Course Studies. 2009.

3.         Verropoulou G, Joshi H. Does mother’s employment conflict with child development? Multilevel analysis of British mothers born in 1958. Journal of Population Economics. 2009 Jul 1;22(3):665–92.

Holland: home of druggies, grannie killers and polygamy

For conservative Christians, the Netherlands must seem like their worst nightmare: legalised prostitution, gay marriage, euthanasia and a liberal drug policy to name a few headline policies. Perhaps than, I shouldn’t be too surprised my country gets dragged into many a political discussion. However, rather than being used as an example of how these policies can work for the best, conservative Christians tend to use them to show how they have turned Holland into a ‘cesspool of corruption and crime’.

Now, I have seen many a cesspool in the Netherlands as I grew up in a very rural area. Crime and corruption however, I didn’t notice that much. Bill O’Reilly of Fox News thinks differently. According to him, the liberal drug policy has made Amsterdam into ‘a Disneyworld for those people’, whatever that may mean. His arguments are easily overturned in the excellent YouTube video below. His rather feeble response to this video (‘They do statistics differently in the Netherlands! It’s a much smaller country!’), prove the points of his challenger rather nicely.

Fox News is not alone in trying to abuse Dutch policies for their own gain. Only a few weeks ago, Rick Santorum announced that euthanasia is used to kill off the elderly population in the Netherlands, who have started wearing ‘do not euthanize me’-bracelets. According to Santorum, 10% of deaths were due to euthanasia, and half of these were involuntary. This time, the Washington Post’s Fact Checker came to our aid and showed that there is not a shred of evidence to back up his claims (I’ll leave you to read the WP piece for more details, as it is rather good).

Last in line to show the evildoings of liberal policies are the UK Christian Institute. Although not as explicit as the above, they claim polygamy has legal status in the Netherlands, and that this form of culture leads to higher levels of robbery, rape, kidnapping fraud and murder. Quite a statement to make. First things first: polygamy is not legal in the Netherlands. Although, as the text rightly states, a so-called ‘cohabitation agreement’ between multiple people is allowed.

This sort of contract, however, is very far removed from a legal marriage. It is a contract you can put together yourself (and have verified by a notary, if you so wish) if you move in with someone, be it your partner(s), or your perhaps your house mates. You can arrange whatever you like in it, from who owns which CDs, to who is responsible for making sure there is enough toilet paper at the end of the week. Sheldon Cooper’s roommate agreement would be a perfect example of a cohabitation agreement.

Sheldon Cooper and his roommate agreement

The 2005 ‘three-way’ case referred to by the Christian Institute was a case of a relationship between one man and two women. However, as they did not wish to marry each other, but merely live together, this is legal in the Netherlands, and you can draw a contract to make it just that bit more official. Cohabitation contracts are popular in the Netherlands, as shown in the figure below. The graph only takes couples into account, and shows that up to 2/3 of unmarried couples – that’s around 450.000 – had a cohabitation agreement in 2008 (the graph wrongly states ‘partnership contract’, but as I have access to the original Dutch data, I can assure you it is on cohabitation agreements). Coincidentally, cohabitation agreements did not arise from the precedent of gay marriage to allow for some form of polygamy, but rather from a desire by unmarried couples to have some agreements in writing, in case their lives together did not work out.

Share of unmarried couples who have drawn up a cohabitation agreement or intend to do so

So, contrary to what the Christian Institute insinuate, polygamy and its rather far-fetched consequences aren’t thriving in the Netherlands. Unfortunately, I don’t have access to the paper they reference, so I can’t comment on the effects of polygamy on crime levels. Although going over the abstract, it reads like an ecological study, which is a type of study that cannot provide evidence for a causal link, only associations. And as we all know: association is not causation.

The world goes viral for Contagion

With a regularity that is comparable to that of the seasonal flu, Hollywood seems to come up with killer virus blockbusters. Most of these seem to operate on plots based on evil megalomaniac scientists infecting escape-savvy monkeys with killer virus-strains, or the archetype bespectacled science boffins who are just too out of touch with reality to come up with a satisfying solution before the military steps in to blast the infected town into oblivion by means of a nuclear bomb. ‘Contagion’, Hollywood’s newest attempt, promises improvement. It aims to realistically portray a global pandemic, and they’ve hired Dr Ian Lipkin, who is the John Snow professor of Epidemiology and head of the Center for Infection and Immunity at Columbia University, to help them get their facts straight (see the video below for his thoughts on making the movie).

[blip.tv http://blip.tv/play/hNVhgs_VPgI width=”480″ height=”300″]

One of those facts is Kate Winslet’s new tagline: “The average person touches their face three to five times every minute”, which opens the film’s ominous trailer and sets the scene for two hours of public health education. With the slightly less cinematic swine flu pandemic fresh in memory, director Steven Soderbergh seems set on using ‘Contagion’ to teach us that despite our recent experiences, we should not take epidemics lightly. It is an ambitious aim for a Hollywood movie, whose main goal undoubtedly is to win their investors’ money back, preferably with an added margin.

The film attempts to show us every single aspect of a pandemic: from the very first infected patient, through its initial global spread, via every single attempt at achieving to produce an effective vaccine and a doubtful homeopathic miracle cure, to the final stages where the world seems to be getting back on its feet. Moreover, the storyline unfolds through a dozen of different characters, each of whom has a complicated backstory and is involved with the virus or the cure in a different way, making it hard to grasp what is going on and what the main story is supposed to be; only the last five minutes appear to be reserved to make that bit clear.

The chaotic sequence of events might make the story a bit haphazard, but it does win points for making the whole thing seem realistic. There is even some actual science in there when epidemiologists start explaining the meaning of the basic reproduction number, or as it is perhaps will be known to all after this film: R0, to a committee of officials to stress the seriousness of the situation. R0 is an important number in infectious disease epidemiology, and indicates how many new infections, on average, one infected person causes. This number ranges from 2 to 3 for your basic household flu, to 12 to 18 for measles and is an important for making the impressive maps that show how fast a particular disease will spread across the world. No wonder then that the officials are duly terrified when it is announced that this number has suddenly sprung from 2 to 5.

The film is a feast for those interested in the topic with all its little sound bites about the ins and outs of epidemiology. Although it does show most of the processes involved in dealing with a pandemic (they’ve left out viruses’ nasty habit of mutating and complicating the whole process of creating vaccines for instance), it might have taken just a bit too much on its plate. Nevertheless, ‘Contagion’ is a pleasant break from the killer-virus genre in that it takes its science seriously, but it might be a bit too serious and realistic to convince the film fans that come in for the big names.

Battle of the stereotypes: girls vs. maths

Picture by XKCD

The Dutch can come with some crazy ideas. Just in the last month, they’ve coined the ‘transfer accelerator’ – a slide that takes you down to the train platform so you don’t have throw yourself down the stairs in order to catch the train when you’re late – and had the rather audacious idea to build a 2 kilometre (±6,500 feet) high mountain to advance their chances of Olympic success in sports like skiing and bob sleighing. The monolith would also serve as a tourist attraction in the country whose highest hill now surmounts to a staggering 322 metres, just losing out to the Eiffel tower. However, not all their ideas are as entertaining as these two examples. Wim Kuipers, chairman of the board of Christian schools in Netherlands, which represents over 800,000 students, has suggested to separate boys and girls for some their classes, such as maths and languages.

Kuipers reasons that boys between the ages of 12 and 16 are, on average, lagging two years behind in brain development compared to girls. He stresses that he doesn’t see the benefit of completely separating boys from girls during their education, but language classes would be a good start, as “girls are often better at languages. If boys keep comparing themselves to girls in this subject, it could discourage them.” He also argues the opposite is true for maths, with boys having the upper hand at this particular subject. Kuipers’ ideas have found fertile ground at the Ministry of Education, as a spokesperson has deemed experiments on his plans ‘conceivable’.

While it is admirable for the Ministry to think of an experiment, it might just be worth looking into the theory and ideas behind Kuipers’ ideas before rushing off to the laboratory. Kuipers makes a lot of assumptions in his statement: he assumes the lag in boy’s brain development (if true) affects their school performance; that girls are better at languages while boys are better at maths and that boys (and maybe also girls, he is a bit vague here) compare themselves as a group to the other sex. While the brain development is a discussion in its own worth, his allegations of girls underperforming in maths and boys in languages are worth looking at in closer detail.

A lot of research has gone into these stereotypes of boys being good with numbers and girls having the advantage where words are the culprit. And for a large part, it does seem to be just that: stereotypes. Research using maths examinations has shown that there does appear to be a difference in average scores for maths for boys and girls, with boys scoring higher. However, this is largely due to something called ‘stereotype threat’: the experience of anxiety in a situation where a person has the potential to confirm a negative stereotype about their social group. This fear, or anxiety, is thought to be due to the constant fear of being viewed through the lens of the stereotype, to constantly having to fight against being stereotyped, and to the worry that any personal failure will be confirmation of the negative group stereotype. In the case of mats exams, it means that girls are afraid to get lower grades because, as girls, they are expected to score lower than boys.

A study conducted in the States (1) showed just that. For the study, male and female psychology students were asked to participate in a maths test. Before the actual test, they received a short brief on what the maths test was actually going to entail. However, in one of the groups, the researchers slipped in a line about girls consistently performing worse than boys in these sort of maths tests, that way creating a group that was exposed to stereotype threat. The results, shown in Figure 1, are quite striking: in the group that was told girls perform worse than boys (high stereotype threat, or ST), girls did just that. However, when the students were not reminded of any gender differences in maths abilities, they performed very similar (low ST group). Unfortunately, the researchers fail to mention exactly how precise their estimations of these different groups of students are (which probably says everything you need to know about how precise it exactly is), but with a limited number of participants (43 students, divided in 4 groups) it was going to be hard to find a real difference anyway. A more interesting find is the stress reaction they measured in girls in the high ST group.

As excruciating as a maths test can be on its own, the researchers went a step further in this experiment and hooked their participants up to a lot of devices to measure their stress and anxiety levels, or proxies thereof. And what do you know: girls in the high ST group had the largest increases in blood pressure and highest increases in skin temperature, both presumed to be indicating stress and/or anxiety experienced during the test, exactly what you might expect as a reaction to stereotype threat.

Figure 1: Number of questions answered right by boys and girls in the high and low stereotype threat (ST) groups (figure from Osborne (2007))

And that is just one study. There are numerous studies showing similar effects of gender stereotypes, or ethnicity-based stereotypes on results on school exams. Some go even further and show that stereotype threat can influence motivation and engagement with a subject such as maths (2). It is a real, and recognised effect that should be taken into account in maths teaching. A rigorous measure as separating girls and boys for maths classes, confirming the stereotype that girls don’t measure up to boys when it comes to number crunching, will thus not only fail to reach its intended effect of improving education, but it will also discourage girls from choosing a career path in which they are already underrepresented. Instead of discouraging girls from taking maths, and boys from exploring the riches of languages, we should aim to stimulate students regardless of their gender.


1.              Osborne JW. Linking Stereotype Threat and Anxiety. Educational Psychology. 2007 Feb;27(1):135–54.

2.              Smith J, Sansone C, White P. The stereotyped task engagement process: The role of interest and achievement motivation. Journal of Educational Psychology. 2007 Feb;99(1):99–114.

The life and times of Paul the perfectly normal octopus: a feature film

Paul the very regular octopus

Picture by Alvaro Felipe

I don’t care about football. To me, it’s just a bunch of guys running across a field being paid enormous amounts of money (Rooney’s weekly salary could fund three entire 3-year PhD studentships) to kick a ball into a net. But the last World Cup did manage to spark my attention. Not because ‘my country’ happened to make it to the final, but because there suddenly was the media hype around Paul, the so-called psychic octopus. Now, psychic animals can provide a good amount of entertainment – let Groundhog Day be the evidence of that – but when people actually start believing in the clairvoyant abilities of a cephalopod something must be awry. With 8 out of 8 correct predictions for World Cup matches last year, the odds did seem to be on Paul’s psychic side, but the feature film “the life and times of Paul the psychic octopus” aims to put those speculations at a rest.

While the trailer is all that is available at the moment, the evidence for Paul’s ability to see the future has been discussed far and wide. As mentioned, Paul predicted 8 out 8 matches right, so the chance of him predicting all of these right by pure luck were 1 in 256 (or 28), which is seemingly a pretty small chance. What actually happened was a bit like a lottery: the chance of one individual guessing the winning numbers is pretty slim, but the chance that someone, anyone, wins is a lot bigger. During the World Cup there were lots of animals trying to predict the outcomes of matches. Mani the parakeet was one of those more famous others who made it pretty far, but there was a vast array of rabbits, horses and guinea pigs doing the same thing. But as with a lottery, only the final winner, the one who guessed (or predicted if you like) all the numbers right made it into the spotlight.

The chances of Paul being psychic seem a lot less when all the other less lucky animals are taken into account. However, there is another aspect to be taken into account: what is the chance that Paul is psychic to start with, and how does the evidence – his 8 right predictions – change this? This is also known as Bayes’ theorem: the chance of something being true is influenced by the initial, or prior, chance. As obscure as that may sound, it is a common feature on a show such as House MD (and in medicine in general). When a slim 18-year old girl gets brought into House’s ward with a heart attack, and all the tests point to a heart attack, Dr House will usually not be convinced as slim 18-year old girls just don’t get heart attacks: it’s a disease for the old and obese. Therefore the cause must be a rare disease that makes it appear as if the girl is experiencing a heart attack and messing up the tests. House always turns out to be right.

The same holds true for Paul: the chances of him being psychic are really low to begin with, if not completely absent (and if you do happen believe that there are lots of animals out there that can see the future, I do hope that you are a vegetarian, as it would be terribly cruel to be killing and eating creatures who know exactly what’s coming for them). The evidence of Paul predicting 8 winners right can, with a bit of maths, be shown to triple the chance of Paul being psychic, as shown here by Prof David Spiegelhalter. As the chance of an octopus being clairvoyant are next to non-existent to begin with, even tripling these chances doesn’t have much of an effect. Interestingly, if you would start out thinking that it is impossible for Paul to be psychic, this would remain true whatever evidence would pop up.

And that are just the statistics. Paul might have guessed the winning team for other reasons. Paul had a real affinity for the German flag, picking it 5 of the 7 times it was presented to him. He might have liked the look of the flag (even though octopodes are practically colour blind), or he might have picked up signals from his German carers, who were rooting for Germany to win. As Germany had a pretty decent team and thus a good chance to win matches, this patriotism might have given Paul an unfair chance compared to his fellow psychics from countries with lesser football teams.

And finally, there were the footballers themselves. They were likely to have heard about Paul and his predictions during the tournament and they are a gullible lot, as evidenced by the popularity of ‘Power balance bracelets’ among them. These bracelets were said to improve balance through “a thin polyester film hologram programmed through a proprietary process which is designed to mimic Eastern philosophies that have been around for hundreds of years,” or to put it in other words: a fancy shiny sticker. All of the players in the World Cup final wore these bracelets, and if they could be convinced that a sticker would improve the ability of players who train relentlessly (or so I may hope for the pay they get), they might as well be swayed by the predictions of a perfectly normal octopus.

Long live the vegetarian?

You might have already noticed, but this week is the National Vegetarian Week, an annual event coordinated by the Vegetarian society highlighting the benefits of vegetarianism. Events promoting a meat-free lifestyle are happening throughout the country in an attempt to get more people to go veggie. While there are a multitude of reasons why you might decide to lay off the flesh, the Vegetarian Society boil it all down to three reasons on their website: the animals, the environment and health & wellbeing. As personal opinions on the first two of those seem to be made up in most of us, the latter is receiving most attention this week.

Call it a lucky coincidence, but at the start of National Vegetarian Week The World Cancer Research Fund (WCRF) has released a report, which, among a lot of other things, advises to limit the intake of red meats and processed meats. Stories of correlations between different kinds of meat and bowel cancer are nothing new; they’ve reached the newspapers time and time again. What’s different this time, is that the WCRF has labeled the evidence linking the two together as ‘convincing’ for the first time. Moreover, the WCRF review also raised the evidence for foods high in fibre, pulses, fruit and vegetables preventing bowel cancer from ‘probable’ to ‘convincing’.

While all that sounds very enticing, it doesn’t directly support the case for vegetarianism. Meat-eaters can choose their meats wisely and as long as they don’t support a solely carnivore lifestyle they could rival any vegetarian in fruit and veg intake. However, there are also some studies comparing the rates of cancer between vegetarians and omnivores. One of these studies is the European Prospective Investigation into Cancer and Nutrition, better now as EPIC. The Oxford arm of this European wide investigation has specifically looked at vegetarians, vegetarians who eat fish (fish-eaters for short) and meat eaters. They followed over 33,000 meat-eaters, 21,000 vegetarians and almost 9,000 fish-eaters over 10 years and assessed the cancers they developed over this period.

Overall, they found that both vegetarians and fish-eaters had a lower risk of being diagnosed with cancer compared with meat-eaters. The risk was particularly lower for both groups of vegetarians in stomach cancer, ovarian cancer, bladder cancer and cancers of the lymphatic and haematopoietic tissues (i.e. leukemia and other cancers of the blood). The effects ranged from a 15% to 71% decrease, which is a truly amazing find. Diet appears to one of the key players in cancer development, but it has appeared rather difficult to put a finger on what elements of diet play a role in the prevention or causation of cancer. A study that finds an effect of this magnitude is thus a real treasure.

However, vegetarians are a weird bunch of people: compared to the general population, they have lower BMIs, are more physically active and gain less weight over time.  Or in other words: they tend to be more health conscious. Where meat-eaters are a greatly diverse lot, with some that will be regulars at fast food chains while others enjoy a healthy diet, vegetarians tend to lean more towards the latter. This makes it harder for researchers to weed out why exactly vegetarians are healthier: is it their lack of meat, their active lifestyles, or another aspect of their lifestyles that is causing their lower cancer rates?

The EPIC study took some of these lifestyle factors into account, be it in a crude way, and still found some beneficial effects of a vegetarian diet. However, that is not to say that meat-eaters, with a balanced diet, would necessarily be at a higher risk of cancer. New research could compare health-conscious meat-eaters with vegetarians to see whether the beneficial effects in vegetarians are due to their lack of meat or their general healthy lifestyle. A healthy lifestyle may thus not be the most convincing reason to go veggie. But as one of those pesky leaf-eating vegans myself, I have to say that the other reasons are very compelling indeed.