Saturday, June 21, 2008

On the Misuse of Statistics

The conventional wisdom holds that something like 0.6% of the population is a part of the Autism Spectrum. This translates to 6 out of 1000 people. That does not sound like much, does it? Schizophrenia, for instance, has been estimated to have a prevalence of 4.6 out of 1000 people1. The National Institutes of Health estimates that 70 out of every 1000 Americans has diabetes2

Now, let us play with the numbers. We could say 6 out of 1000, but we could also say 1 out of 150. The two figures are approximately the same. "OMG! 1 out of 150!?" is probably the reaction of most people when they hear 1/150. The thing is, 6/1000 does not sound as bad, because most of us do not think they know a thousand people. A percentage like 0.6% does not sound that big. But 1 in 150? Most folks are acquainted with at least 150 people. It is a number that is easy for the mind to wrap itself around.

Accusations are often hurled at people who espouse Neurodiversity, by those who have agendas of their own. Neurodiversitists3, they say, are not "really" Autistic. Either that, or we are not "representative" of the "Autism Community".

I believe that it is presumptuous for anyone to declare that someone like me is not "really Autistic". If you are an "autism mom" reading this, feeling incensed that some pretender is mocking your child's condition, by claiming to be autistic, please remember that you do not know me. You did not grow up having to struggle to understand social cues, or dealing with the awkwardness of being the "weird kid" in school. You have never spoken with my teachers or my parents. I suppose you might think that because I graduated from a prestigious university and can hold down a job, I can be called "high functioning" and not be considered to have any problems.

The reason that I could be labeled as "high functioning" is that over the years, I have developed my own methods for dealing with the larger world. These tools, however, are things that I have worked out cognitively; there is nothing instinctual about them. Most people are able to handle the give and take of conversation, whether it be small talk or flirting. I can speak easily enough with people that I know well, but it take considerable mental effort for me to hold a conversation with a complete stranger. Afterwards, I feel that I need to be alone, in order to let out the pressure inside of me.

On the other hand, being on the Spectrum has helped me a lot. I am not one of those AspiePride people who think we have "superpowers", but I do believe that my talents more than compensate any sort of social awkwardness that I may still have, Like many of us, I do think in pictures and my spatial reasoning is very well developed. I have always been very good with Mathematics. My understanding of it has always been very intuitive; I have hardly had to think about it in order to learn something new. This has helped me a lot in developing computer software. It is all about algorithms. They just snap into place in my head, without giving them much thought. Recently, I have started learning to play the piano. The music theory has come very easily to me. The hard part is getting my hands to co├Ârdinate themselves.

Then there is the debate over whether people like me are "really representative" of people who are on the Spectrum. Usually, these arguments come from people who are pushing one agenda or another, whether it be a "cure" for Autism, mercury or other toxic metals, or the idea of the "Indigo Children"4. We are an affront to their deeply cherished conspiracy theories, because we get along just fine without them and their "help".

S.L., writes about this in her excellent blog. In "High Functioning? Then Shut Up!", she lays out an interesting conundrum. Autism Speaks and the Mercury Militia crowd present a picture of Autistic people as a bunch of children who violently act out, fling feces, bang their heads against walls, and make their parents' lives a living hell. Anyone who does not fit this model is not "really" Autistic, according to these people.

On the other hand, S.L. opines, these same groups are very inclusive of us when it comes to compiling statistics. How else could one gin up a figure of 1 in 150?

I will go even further. Just how representative are the "autism moms" in the Spectrum. I have not seen any hard evidence going either way, but my hunch is that they are not very representative at all. An elementary knowledge of statistics and probability theory will tell you that extreme cases are very rare and that a population will tend towards a mean. This is the reason why Einstein's children did not become extraordinary scientists, or Mozart's children did not become great musicians: Einstein and Mozart were enormously talented and gifted men, far off to the right on the distribution curve of genius. Most people are not geniuses, and will be somewhere close to the mean, well within the standard deviation.

The same is very likely to be true of how people on the Autism Spectrum are distributed. Simon Baron-Cohen5 has suggested that everyone has varying degrees of empathizing and systemizing, and that how much or how little of each quality one has, depends a lot on one's genetics. In general, he says that males are better at systemizing and females are better at empathizing. There are exceptions, people who do not fall within the standard deviation about the mean.

Diagram of a Standard Deviation
Image created by Peter Strandmark. Used under the Creative Commons License.

People on the Spectrum, Simon-Cohen believes, are people who are outside of the standard deviation, falling on the left side of the empathizing curve and falling on the right side of the systemizing curve. Extreme cases, those on the tail ends of the curve, are very rare.

How rare? Nobody knows for sure, however, it is unlikely that the extreme cases form the majority of those on the Spectrum. What is more probable, is that the spectrum is mostly made up of people who range between "high-functioning" and "needs help with some things in order to get by." Many of us are grown-ups who have jobs and families and stuff. Hardly the feces-smearing children portrayed by Autism Speaks.


  1. "How Prevalent is Schizophrenia?" PLoS Med (2005) 2(5): e146
  2. National Institute of Diabetes and Digestive and Kidney Diseases. National Diabetes Statistics fact sheet: general information and national estimates on diabetes in the United States, 2005. Bethesda, MD: U.S. Department of Health and Human Services, National Institute of Health, 2005.
  3. Look everyone! I believe I have invented a new word!
  4. Finally! A set of beliefs even sillier and stupider than those espoused by the Mercury Militia.
  5. Baron-Cohen, S. (2003), The Essential Difference: Male and Female Brains and the Truth About Autism, New York, Basic Books ISBN 0-465-00556-X

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