Huge results from a relatively simple action

Woof!  A standard deviation improvement in IQ and an 11% increase in productivity.  That was a time of low hanging fruit and material gains in effect sizes.  

Unsung public health hero: Dr. Crowie, a doctor from Michigan, noticed that many from the Midwest had goiters. He convinced Morton Salt to voluntarily add iodine to salt in 1924. The results were insane as average IQ went up 15 points across much of the US! Income went up by 11%! pic.twitter.com/YaAFvatgik

— Ethan Mollick (@emollick) February 7, 2021