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nbme23/Block 4/Question#10

A study was conducted to investigate the mean age ...

99%

+24  upvote downvote
submitted by yotsubato(520),

Was it just me, or did "age at onset in years" appear RIGHT above the number of patients, rather than the mean. Which confused me for a good 3 minutes.

fulminant_life  Definitely was the same for me. I was so confused for like 5 mins +7
d_holles  dude i almost didn't get the question bc of this ... i thought the age of onset was the actual age of onset (36) +4
mellowpenguins  Are you serious. NBME strikes again with shitty formatting. +4
yex  OMG!! Now I just realized that. Super confused and also thought onset of age was 36. :-/ +4
monkey  what is 36 supposed to be? +
thomasburton  Think the number of people in that group +1
paulkarr  Yup...was looking at it for a good 3 min before just doing the "fuck it..it's gotta be 99" +
arcanumm  Age of Onset is the Title of the table, which I didn't figure out until after exam was over. What terrible formatting. +

+6  upvote downvote
submitted by mcl(377),

This figure is a helpful refresher for the 68/95/99.7 rule

Why is it 99% and not 95%? It asked for onset of disease at less than 9 years of age. I'm clearly missing something here

cbrodo  @fulminant_life because the mean age is 3.8 with a standard deviation of 1.8. An age of onset of 9 years is nearly 3 standard deviations above the mean. Therefore, since we know +/- 2 SD covers 95% of the bell curve, it must be higher than that. The only option higher than 95% is 99%. +8
charcot_bouchard  Yes 9.2 was the upper limit for 99% CI. I picked 95 first because i thought 2.5% would be out of this range. But changed ans because it should be less than 2.5% because 9.2 is so close to 9. Also they are asking CLOSEST to which of the following? +