Anecdotes are not Evidence

Anecdotes make for entertaining or frightening stories. They add spice to life and help give others a sense of what you, personally, have gone through. I'm all for anecdotes. The world would be sorrier for lack of them.

Where we run into trouble is when an anecdote is held help as evidence to support a hypothesis.



See, the problem here is that an anecdote is singular and isolated. That's right there in the definition:

"Anecdote /ˈænɪkˌdoʊt/ Show Spelled Pronunciation [an-ik-doht]
–noun: a short account of a particular incident or event of an interesting or amusing nature, often biographical. "

One incident a pattern is not. Let's examine a recent example.

Over at Ari's blog, when he ranted about proper SL business practices, I brought up the sordid story of my own experience with a rather nasty content creator. And oh the trouble he caused! And the terrible taste in my mouth after the entire experience. It was really touching, like watching orphans shed tears.

But does it really prove anything? No, not particularly. The only thing it proves is that one should not patronize that store. It does not really say anything about the state of Second Life business owners in general. Who knows? Perhaps the majority are kind to a fault and I just happened to luck out and hit the outlier.

Outlier. Now that is a word. " A statistical observation that is markedly different in value from the others of the sample". A single outlier can be an anomaly. If one person spontaneously combusts, and a million don't, it's safe to say Mr. Fireball is an outlier, outside of the norm. He's an amusing anecdote.

Why do I bring this all up? I'll get to the point, I swear!

The point is that all too often, when I read blog comments, people confuse anecdotes with evidence. Specifically, reading a blog post about vaccinations. Let it be known, above all, that I'm totally pro-vaccination. Smallpox and polio and anthrax are high on my list of things I do not want. I've read what those diseases were like, and it is not fun. But back to the point!

One genius stated that he never got vaccinated, ever, in his entire life, and he never became ill with any disease. Why do we need vaccines, pondered WonderMan, if he could walk around for thirty-odd years with nary but a cough?

You're an anecdote. An outlier. Your experience is not the norm. You can wander the country and never fear measles because most of the rest of the country is vaccinated and your likelihood of contracting it from such a population is low. Nonexistent, even. Similarly, I could claim that there is no need for vitamins, for I eat very healthy and have never had a vitamin deficiency. Never mind the fact that I have access to and can afford such food (which is often not available to others, particularly vulnerable populations such as, uh, the poor). My case for discontinuing vitamins is sound due to my anecdote!

Can you see why we can't use a singular example to prove a point? Need another?

One child was hit in the head by a home runned ball in a Yankees game. We should probably ban baseball because it's a very dangerous sport for the spectators. All those home runs, the stands should be drenched in red with the blood of its victims. Unless you're in Philly, in which case blood drenched is the norm (becuz we r violent dur dur dur). Let's ban baseball. Nevermind the fact that of the thousands upon thousands of games, only once was a fan killed by a home run ball landing square on the cranium. Damn, that outlier has me convinced!

Why are anecdotes so effective in swaying us, then? You're probably itching to ask me, "Well, Anna, it's easy to see how a single anecdote does not a case make, who could possibly fall for it?" My friend, meet the emotion. Would you want your children killed at a ball game? Would you want to unnecessarily jab your children with needles if there was no worry of the disease? Of course. So, in the face of reason, people believe this. They focus upon it.

This is bad when the anecdote is outside the norm and thus is something we don't need to fear or when it is not related to the discussion at hand at all. I could cause a panic by noting the rise in autism coincides with the mass production of teeth whitening tooth paste. Does it make it true? If I give you a story of how my child developed autism after I brushed his teeth with tooth whitening Crest, does it mean there is a Crest conspiracy out there preventing the truth from being heard?

Should we ban toothpaste?

The problem with anecdotes are that they are emotional, spur of the moment, and sometimes irrelevant. The next time we hear a story which causes our hearts to pound and incite the urge to take up some cause, please calm down, be rational, and try to study the problem before leaping to conclusions. I see all too often in Second Life, among other places, where one person will mention something or other about some aspect involving copybot and the mob attacks without pausing to truly examine the situation.

Please, be patient and don't jump to conclusion on the basis of a single (or even a few) story. Further examination may reveal it to be untrue or unrelated.

As for me, I cannot say I am a saint. More than once I've leapt on something without bothering to stop and think about it. But on the whole, I try. I try. And that's all you can ask for.