Hi Hsien,

I’ve been reading The Tiger That Isn’t, a book about innumeracy (the numerical version of illiteracy). It’s sort of an updated version of the classic How To Lie With Statistics, but with an eye toward the mainstream media (MSM) and public policy.

In the chapter on risk, the authors point out that the MSM often reports increases in risk as “70% higher” without reporting the baseline or average risk. They suggest that skeptical (or just honest) readers should ask, “70% compared to what?”

The NIMH reports that the adult prevalence of bipolar disorder is 2.6%. So the authors of Tiger would suggest that MSM reports read more like the following:

“The average American has a 2.6% chance of having bipolar disorder. Siblings with an identical twin who has bipolar disorder have a 4.4% chance. People who have one parent with bipolar disorder have a 2.8-2.9% chance of becoming bipolar, while those with two bipolar parents have a 3.1% chance.”

Why does the MSM like to report it the first way? Simply because normalizing against the average risk makes bigger numbers and sells more papers/airtime/adclicks! A “20% increase” sounds much more serious than having a 3.1% chance compared to a 2.6% chance, even though they mean exactly the same thing.

Reporting the baseline risk is important because it underscores the fact that even though there may be a genetic component to conditions like bipolar disorder, genetics are not deterministic for many of the most common diseases.

Andro

[...] Lei gave me and bipolar disorder an awesome shout out today at her fabulous blog Eye on DNA: Genetics of Bipolar Disorder and Hypomania. (Is “shout out” the appropriate term to use when one refers to information about and [...]

Hsien: You make me blush.

Right before the event that led to my finally seeing a professional, and eventually getting diagnosed, I was hypomanic for…geez…well, a long time. Severely, then not-so-severely, then manic, then hypo again. I was mostly hypo for years. It was…well, at the time it was wonderful. I worked 2 jobs (one was my actual full-time career, the other was a job I picked up in college and just couldn’t give up?!), 6 or 7 days/nights a week, slept 2-3 hours a night/morning, and managed to have a…very “interesting” social life. I felt like everything I touched turned to gold, because everything was so successful. Of course, I was on the eve of mania, then crashing, then total disaster.

I’m now stuck in knowing how good it can be, how bad it can turn, and not knowing how to get back to it even if I knew how to balance it.

But, I’m getting off on a tangent.

Ah, I can’t wait to dig into these links! Thank you so much!

Andro: Excellent observation.

[...] NB: Andro Hsu of 23andMe has made a similar point in the past about presenting risk information. [...]

Hi there,

In light of Andro’s observation, may I ask whether the ‘20 percent chance’ from two bipolar parents is a hard number or whether it is 20% higher?

Cheers,
Kaila

[...] October, Dr. Hsien-Hsien Lei of Eye On DNA highlighted information regarding bipolar disorder and genetics (and published a picture of me wearing the exact tee shirt I’m wearing right now - funny, [...]