I’ve only read the abstract as the full PDF seems to be paywalled, but the 15 points of gain seem to be limited to “the one quarter of the population most deficient in iodine”. The abstract says the estimated gain for the population as a whole was “roughly one decade’s worth of the upwardtrend [sic] in IQ in the US”, which is 3 points (from memory).
A new study shows that a major part of the Flynn effect in the US was due to iodine in salt. The study suggests that around 15 points of the non-normalized IQ gain was due to this.
I don’t know about Flynn, but this is in large part not new news: that the early 1920s US iodization led to measurable gains in enlistees for WWII has been in papers floating around for a while now; for example, “The Economic Effects of Micronutrient Deficiency: Evidence from Salt Iodization in the United States”, Feyrer et al 2008. “The Impact of Iodine Deficiency Eradication on Schooling: Evidence from the Introduction of Iodized Salt in Switzerland”, Politi 2010, is also cool. Also maybe even voting patterns.
(Citations borrowed from my iodine page.)
I think the paper JoshuaZ’s linked is a completed version of that 2008 draft: the authors are the same and the title & abstract are similar.
That link doesn’t work for me.
Maybe. I haven’t read it yet but I copied it over to http://dl.dropboxusercontent.com/u/182368464/2013-feyrer.pdf
Oh, sorry. They redirected the page instead of using a 404 error, grr, no wonder my
linkchecker
runs didn’t pick it up. This link should work: http://web.archive.org/web/20120926070411/http://www.uncg.edu/bae/econ/seminars/2012/Bednar.pdfThat’s helpful, thanks!
I’ve only read the abstract as the full PDF seems to be paywalled, but the 15 points of gain seem to be limited to “the one quarter of the population most deficient in iodine”. The abstract says the estimated gain for the population as a whole was “roughly one decade’s worth of the upwardtrend [sic] in IQ in the US”, which is 3 points (from memory).
Yes, thanks for pointing that out. I was aware of that but apparently phrased it really badly in my summary.