In the ensuing discussion a poster noticed that the journal article contains an elementary math error:
"if schizophrenia occurs at a rate of 0.72% in the population (McGrath et al., 2008) and congenital blindness occurs at an estimated rate of 0.03% in people born in the 1970s and 1980s (based on Robinson et al., 1987), then the joint probability of a person having both conditions, if the two are independent, would be 0.02% or 2 out of every 10,000."
0.72% * 0.03% is actually .0002% or 2 out of every 1,000,000.
Despite the article being several years old, I thought you might want to know.
Thank you for your effort.
For someone who is in academia and a firm believer in the advancement of knowledge via peer-review, these things matter. Cheers!
it is probably not a math mistake since, when they applied the probability the 620 people is correct. Might be a typesetting (formatting) mistake. The 0.0002 is already a percent, but someone overlooked that and turned it again into percent.
Still it should definitely be corrected as the 2 out of 10,000 is a value that sticks in the mind.
I once helped setting an article in tex (originally written in word) and made the mistake of not noticing that rich text 10^20 got converted to 1020 in plain text. We only noticed post print but nobody else seem to have stumbled on it even though it was at the core of the articles thesis.
Weirdly, as ChrisRR points out, they get the total number of predicted blind + scizophrenic people in the US correct. So it almost looks like more of a typo than a math error.
