She Blinded Me with “Science”
My post on vaccines and autism was so well received (as in, a few people actually commented, which made me VERY happy), that I started thinking.
I do do that, on occasion.
Spurred on by A Lawyer Mom, who uses her superpower capability for reading political and legal briefs to teach us everything we need to know about the economy, and the Geithner Plan, and the subprime mortgage mess, I remembered that old Chinese proverb:
If you give a mom a scientific paper analysis, you protect her family for the day; if you teach a mom to analyze a scientific paper, you protect her family for a lifetime.I think something got lost in translation, but you get the basic idea.
So, welcome to the first installment of a new feature on this blog.
From time to time (as in, when some great example presents itself and I feel like doing the research), I will be posting some basic information on how to evaluate “scientific” data.
Let me preface this by noting: There’s a LOT of bad science out there.
And then there’s good science, hyped out of proportion by the media, who can turn even mediocre studies and insignificant results into major news events that get people like Jenny McCarthy all riled up.
There are a few important things that we all need to know when we look at “science” and media hype.
Our first topic: distinguishing the difference between “association” and “causation.”
The association argument goes something like this:
A is often found together with B. Therefore, A and B are causally related.
This is the argument used to convince folks that vaccines and autism are related. They both happen at about the same time in a youngster’s life. The incidence of autism increased sharply about the same time as the introduction of the modern vaccine schedule. Therefore, vaccines and autism are causally related. And since no one is likely to claim that autism causes vaccines, it has to be the other way around.
Convinced?
Here’s a recent example of a study that got a lot of press that uses this line of reasoning. The headline: Scientists find Baffling Link between Autism and Vinyl Flooring. (I found this through the Improbable Research Blog, run by the same folks who give us the Ig Noble Prize. In their words, “Research that Makes People Laugh, then Makes them Think.”)
The study was conducted as a self-reported survey designed to look at environmental pollution and asthma. One of the questions on the survey asked about autism. Quite by accident, an association was found between self-reported (by the parents, obviously) autism and vinyl flooring.
[Out of 4779 study participants, there were 72 cases of autism. The report says that the risk of autism "doubled" with vinyl flooring, so that means, I assume, that 24 autistic kids lived on carpets and 48 autistic kids lived on vinyl. (More about how to evaluate statistics like this in future installments. For now? NOT SIGNIFICANT. Trust me.)
The study also found an association between autism and maternal smoking (which has been decreasing, BTW, while autism rates go up), condensation on windows, and family economic problems. Whew. It's a good thing that my kids are past the autism age during this recession.]
This, my friends, is an ASSOCIATION. It says nothing about the causation of autism (or vinyl floors, for that matter. As has been pointed out regularly in criticism of this study, autism is genetic. Autistic kids frequently have autism-spectrum parents, who may be subconsciously CHOOSING vinyl flooring, as autism-spectrum patients often have textural issues–so it’s just as plausible that autism causes vinyl flooring).
Here’s an example of association that everyone can enjoy, just to get the point across.
Statistically, most auto accidents occur on the way home from the grocery store. The most common purchase at a grocery store is carrots. Therefore–having carrots in your car massively increases your risk of an auto accident.
Do carrots cause auto accidents?
Maybe these seemingly innocuous vegetables are really aliens in disguise, sending out telepathic vibes that mess with your driving.
It could happen, right?
Another “association” is the “post hoc, ergo prompter hoc” argument (it happened after, therefore caused by). This is the one that the autism/vaccine folks use the most. The kid was fine before the vaccine, then he had the vaccine, and then he began to show signs of autism.
The rooster crows just before dawn. Then the sun comes up. So, therefore, the rooster crowing makes the sun rise. And if someone kills the rooster, the earth will be plunged into eternal darkness.
This is the logic of magical thinking.
If we throw virgins into the volcano, it doesn’t erupt. If the volcano then does erupt, it just means we haven’t thrown enough virgins into the volcano.
The problem with post hoc ergo prompter hoc is that things just happen. One thing has to come before another. It does not (necessarily) mean that the first thing and the second thing are at all related.
Until we understand the actual science of the sun rising or the volcano erupting, we have to be very careful of our associations.
Otherwise, we’ll get a lot of virgins really hot for no good reason.
And a lot of kids dying of vaccine preventable disease.
Watch out for those vinyl floors. I spilled water on one once. Then I slipped.
If you enjoyed this post, make sure you subscribe to my RSS feed!Related posts:
- To Science, or Not to Science
- Science and the Death of Helicopter Parenting
- The Great Texas Science Panic
- The Jenny McCarthy Body Count
- What’s Wrong with this Study, page 2
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22 Comments
The Dental Maven
Thursday, 16th April 2009 at 4:19 pm
Well that settles it. NO MORE CARROTS in the Maven household!
The Dental Maven’s last blog post..Never Run (Or Floss) With Scissors
themother Replies:
April 16th, 2009 at 4:37 pm
Ah, see? I KNEW I could help people think more clearly!
Risa
Thursday, 16th April 2009 at 4:48 pm
Interesting posts. I did a couple degrees in philosophy, so I am well-versed in fallacious arguments, and agree there are a lot of bad ones out there when it comes to vaccines (and medicine in general, actually). But–you saw the ‘but’ coming, right? –there is one thing about vaccines that I have never seen addressed, and I want to know the answer to: Why do different countries adopt different vaccine schedules? There are differences between countries of the ‘western-world’ sort, presumably whose scientists have read / conducted the same studies, and adopt the same starting principles: mainstream western science. Yet the vaccines given to children in the US, or the UK, or Canada, or Sweden, or Japan differ: in timing, in which vaccines, in whether they are given singly or as a group. I am not saying vaccines don’t save lives or that vaccines are bad; I am just a reflective person wondering, “Why the difference in vaccine protocol, if informed by experts who have access to the same studies / information?”
Risa’s last blog post..Math Games: Addition War and Make 10 Go Fish
themother Replies:
April 16th, 2009 at 5:37 pm
In America, the vaccine schedule is recommended by the American Academy of Pediatrics. They have a panel of experts who review the data, hash it over, and publish their reports. Their recommendations are based on such things as immune response (very young children develop the ability to react to vaccines at specific times), the epidemiology of the disease (it’s more important to vaccinate early for diseases that happen in early childhood or that affect fetuses in utero), and the adjuvant effects of the vaccines themselves (some antigens work better if given together, and so the total dose can be lower).
Every country has access to essentially the same data, but there may be slightly different epidemiological concerns (for instance, Polio is still endemic in India). Different health care policies may affect the delivery schedule. Plus some of it is just a “this is the way it has always been” kind of thing (if it ain’t broke…).
I am unaware of any MASSIVE differences in vaccine schedules, but I also haven’t had much experience outside of the US. I’ll see what I can find out and get back to you.
Helene
Thursday, 16th April 2009 at 5:07 pm
I definitely love the analogy of the carrots and car accidents….did they specify between baby carrots and regular carrots? That’s what I really wanna know.
Okay, seriously, though, I remember awehile back talking to Cole and Bella’s former EI therapist and she said the same exact thing about autism, not about vinyl flooring but that the signs of autism are usually most prevalent around 18 months old, which is normally when most children receive the MMR. There’s no causation between the two….it just happens to be a convenient coincidence is how she explained it. I wish more people would understand that.
Helene’s last blog post..The Beginning….Infertility, my cross to bear….
themother Replies:
April 16th, 2009 at 5:20 pm
I don’t have the data to answer the carrot question. I’ll have to get back to you.
Jen
Thursday, 16th April 2009 at 5:29 pm
I just want to add that when bad things happen we want to find someone to blame. My daughter was born with Spina Bifida and Anencephaly, both neural tube defects. If I recall correctly the defect came into play in the first trimester. Now we know that folic acid plays a big role in preventing these defects, sadly only months after this happened. When my husband was told what was going on he immediately blamed me and my genes. It was a knee jerk reaction. I of course wanted to blame his genes. I know this is not the same thing but parents want to do the best for their kids and so when a child is born with a disorder that makes their life challenging the parents want to blame someone or thing.
Jen’s last blog post..Matchmaking Update
stepiphany
Thursday, 16th April 2009 at 6:14 pm
Bravo!
stepiphany’s last blog post..is this middle age?
Liz
Thursday, 16th April 2009 at 8:46 pm
… there’s condensation on my windows sometimes…. my kids are doomed.
Liz’s last blog post..Operation Repo: Revisited
themother Replies:
April 17th, 2009 at 7:59 am
But the important question is: Do you eat carrots?
AmyAnne
Thursday, 16th April 2009 at 10:58 pm
Thanks for this. I’ll call it the How To Use Your Brain series.
I believe also, the recommended vaccine schedule takes into consideration when we are most likely to have access to the greatest number of kids in a medical facility. Like when they are first born.
AmyAnne’s last blog post..I’ve a Feeling We’re Not in Kansas Any More
themother Replies:
April 17th, 2009 at 8:01 am
Yes, as I mentioned in the comments on the last vaccine post, one of the reasons we give SO many in infancy (for diseases they aren’t likely to contract until they’re older, is simply the logistics of getting them BACK to the pediatrician when they’re older. Plus young kids are easier to vaccinate. You don’t need five strong men and a roll of duct tape.
The Lawyer Mom
Friday, 17th April 2009 at 9:46 am
Interesting stuff. I heard about a study out of Cornell (but not the medical department) that found an association (or is it high correlation?) between autism with harsh climates. The theory was that when the weather’s bad outside, children watch tv and tv causes autism. Hmm. I’m thinking the tv watching was happening on a vinyl floor while the children were eating carrots.
Seriously, very informative post, Mother.
The Lawyer Mom’s last blog post..The Great Geithner Heist
Momisodes
Friday, 17th April 2009 at 9:51 pm
I loved this post.
I even forwarded this off to a few others.
I get vaccine/autism questions all the time from parents. I may consider sending this to them as a response
Momisodes’s last blog post..Two-timing may be hereditary
mrsbear
Friday, 17th April 2009 at 10:57 pm
You really put it in to perspective. Personally I don’t buy carrots, since none of the kids eat them. I’m pretty confident I won’t get into any post-grocery auto accidents. Now that rooster thing, that concerns me a little.
Our former pediatrician actually held off on vaccinating kids who showed early signs of autism, just because he didn’t want the vaccine to be linked as the “cause”. This was before he stopped taking budgetary short cuts and bypassing vaccine purchases altogether. But that’s a whole other story.
Thanks for updating the links btw. I appreciate it.
Wendy
Saturday, 18th April 2009 at 11:18 am
What you’re reminding me of is that stupid “calcium makes you lose weight” study. I looked at the details of the study a little and found that the participants were eating TEN little tubs of yogurt per day, as a replacement for two of their meals.
That is called CALORIE REDUCTION! Not CALCIUM BENEFIT. So, so stupid.
I took a child psychology class in college, thinking it would be great to take as a very new mom. The only thing I really took away from that class?
That the main point of any study is to manipulate data in such a way as to fund the NEXT study and keep oneself employed in that way. And that even the most innocuous and unrelated data can be manipulated enough to get some sort of result.
Don’t make it true.
Wendy’s last blog post..No. Means. NO.
Darla
Saturday, 18th April 2009 at 5:16 pm
I love how you dumbed that down even for some one like me who is scientifically challenged.
Darla’s last blog post..Sofa Tables
the Mayor
Sunday, 19th April 2009 at 6:50 pm
Maybe it’s because I just finished your post on Amazon/pornography censorship but my first thought after reading your scientific data primer was: how long can a hot virgin remain a virgin?
Can that be measured in weeks, months, years?
the Mayor’s last blog post..Anger & Rage?
themother Replies:
April 19th, 2009 at 7:17 pm
I haven’t seen a study on that. I’ll have to get back to you.
Amy
Wednesday, 22nd April 2009 at 8:23 am
Thanks for this post. I’ve thought similar things many times when I hear all the coverage in the media. I wish commentary like yours made it out there more.
Amy’s last blog post..Does Having Children Make You Happier?
Hazel
Wednesday, 1st July 2009 at 11:45 am
Mother, there's a new BBC article which I think relates very well to this, stating in the headline that vegetarians avoid more cancers.
I think it's a superb example of what you were saying here. The actual article says that more research is needed before people change their diets radically, but the headline screams that vegetarians avoid more cancers, so that is probably what will stick in peoples' heads.
http://news.bbc.co.uk/1/hi/health/8127215.stm
TheMother Replies:
July 1st, 2009 at 2:03 pm
And yet again, it's probably associative. Vegans tend to live cleaner lifestyles to begin with. They are thinner, generally don't smoke, and avoid any number of other vices. If you treat your body like a temple, good things happen.
Although for colon cancer, it's pretty well documented. Higher fiber content, and lower intake of nitrates, equals lower colon cancer rates.