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JoshuaZ comments on Open thread, July 23-29, 2013 - Less Wrong Discussion

9 Post author: David_Gerard 22 July 2013 10:34AM

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Comment author: JoshuaZ 23 July 2013 11:23:53PM 12 points [-]

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.

Comment author: gwern 24 July 2013 04:21:22AM 8 points [-]

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.)

Comment author: satt 25 July 2013 02:48:34AM 3 points [-]

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.

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.

Also maybe even voting patterns.

That link doesn't work for me.

Comment author: gwern 27 July 2013 06:33:43PM 1 point [-]

Maybe. I haven't read it yet but I copied it over to http://dl.dropboxusercontent.com/u/182368464/2013-feyrer.pdf

That link doesn't work for me.

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.pdf

Comment author: satt 27 July 2013 06:54:24PM 0 points [-]

That's helpful, thanks!

Comment author: satt 24 July 2013 03:00:23AM 5 points [-]

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).

Comment author: JoshuaZ 24 July 2013 03:13:31AM 2 points [-]

Yes, thanks for pointing that out. I was aware of that but apparently phrased it really badly in my summary.

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