Correlation is not causation

I’d like to tell a tale of why vaccines don’t cause autism or encephalitis or whatever people are blaming them for these days. Wait! This isn’t a lecture, just an explanation of how any person can be fooled by a correlation, even me 🙂

Last year, my daughter Yael got conjunctivits (aka pinkeye) and was put on an antibiotic. A few hours after taking the antibiotic, she woke up gasping and choking and generally very miserable. Since it was the second time she’d taken this particular drug, I wondered if she could be having an allergic reaction to it. I had a bit of a freakout, got her to take some Benadryl (just in case) and took her to the doctor in the morning (still slightly freaked out).

The doctor calmly explained that Yael had croup. Which I should have recognized, because Barak had already had it twice by that point. But I was so distracted by the coincidence of her having taken a medication, I just assumed the drug was at fault.

So what we had was a correlation: antibiotic is followed by choking and gasping for breath. But the cause of the gasping wasn’t the antibiotic. Most likely, the same virus that gave her pinkeye also caused the swelling around the vocal chords that is called croup.

I can understand why someone whose child gets sick after getting a vaccination might think the vaccination is at fault. Really, I can. But you need to be able to look past the correlations to find the causation.


About mamamara

I'm a 40-something, work-at-home mother of two. I'm pro-vaccine, pro-medicine, pro-science, and an avid reader of information about all of the above, and I want to combine my love for my children with my love for science. So here we are!
This entry was posted in Medicine, Vaccines. Bookmark the permalink.

2 Responses to Correlation is not causation

  1. Pauline MacDonald says:

    Unfortunately, for many, our “logic is faulty” our children are concerned. Compound that with the common problems of logical fallacies. and voilà , events connected by time and correlation suddenly have causative powers imbued upon them.


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