11/n Next, the authors did something odd. They decided to compare this to the DIRECT mortality from COVID-19. This means that they are only counting people who have died as a direct result of the diseasepic.twitter.com/MQiG2PapOc
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22/n Ok, there's another HUGE problem with the study The findings are entirely based on the idea that an extra year of schooling reduces your risk of death by 25%, a figure reached by aggregating studies in a meta-analysis modelpic.twitter.com/va8PWXeBc3
23/n This number is the ENTIRE BASIS for the paper. If schooling reduces mortality by less than 25%, then the number of deaths caused by missed school days will drop as well And we have a problem, because this 25% figure is...wrong
24/n Firstly, we have these top 2 papers. Because they're from the US, they are more heavily weighted than the others (this is arbitrary, but whatever) Except the values for the second paper are flatly incorrectpic.twitter.com/VxC2Krkj3z
25/n Mazumder (2008) did not find a relative risk of 0.65 (0-1.3), it found an RR of 0.89 (0.74-1.04) The paper is here. I've read it very carefully and this appears to be the main finding from the author https://www.chicagofed.org/publications/economic-perspectives/2008/2qtr2008-part1-mazumder …pic.twitter.com/1FY15LCXFe
26/n So the number is wrong, but this brings us to another issue - the two papers at the top that were double-weighted...are ON THE SAME DATASET This is a massive issuepic.twitter.com/trCaHySTYE
27/n You see, Lleras-Muney compiled an estimate based on a number of factors on the reduction in risk from 1 year of extra schooling. Mazumder, three years later, took that same database and re-analyzed it considering additional factors, and estimated a lower reductionpic.twitter.com/2pWUNsP6Qb
28/n However you slice it, it's inappropriate to just bung these two estimates together into a model and treat them as separate. I would argue that the Mazumder paper is probably a better estimate, but either way what they've done here is wrong
29/n If I re-run the meta-analysis they've purported to use with the correct numbers, we end up with this graph instead. A relative reduction in risk of death of 5% for every year of schooling This is A QUARTER of the estimate used in the studypic.twitter.com/xQk5F1tDzT
30/n So AT BEST assuming there are no other errors, the estimate of the years of life lost due to school closures should be divided by 5
This last tweet is where I am on the issue. The trauma of increased deaths & disability among parents & caregivers will have an outsized effect on both YLL & educational attainment. There's no way to test the counterfactual in this, but intuitively it's such a major factor.
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