Talking to Hart about hormonal birth control, migraine and stroke risk got me wondering what my risk really is. If it is low, multiplying the number by eight isn’t that big of a deal. Kersti explains this well in her comment on the post:
[T]he problem with statistics is that they’re misleading. 8 times more likely… 8 times what? You need to find out what the baseline actually is, and you need to find it out for your own ethnicity, gender, circumstances before you know if this is a problem. If for example the baseline is 10% then 8 times is pretty ghastly, however, if the baseline is 0.01% then you’re still at 8 times 99.92% likely to NOT get one.
I’m kind of embarrassed I didn’t think this through before I wrote the post. I’m always urging readers to think critically. No matter how much I recommend caution, I too fall into the trap of fear. “Stroke? Eight times more likely? No way!” is how I reacted yesterday.
According to the American Heart Association’s stroke risk factors, I’m at very little risk. That’s reassuring. I’ll talk with the doctor on Monday and see what she recommends.
Check out the this BBC article on understanding — and critically evaluating — statistics, which Kersti suggested.