Something you might want to consider in the future is going into the claims made by the book slightly more. While I was reading this, I found myself constantly thinking “Yeah, but should I trust this study?”. It sounds like you’ve looked into this and find them convincing, but I personally would have found it useful to include a little bit more information, like “How big was the study?”, “Was it observational or experimental?”, “Has anyone reproduced the results?”.
The part I was most skeptical of is:
Students were free to come to school one hour earlier than usual and spend that hour exercising. They performed fitness activities such as running rather than team sports, where there can be a lot of waiting around and a much more diluted exercise.
It sounds like there’s a pretty major confounder here if group A is “kids who chose to go to school an hour earlier” and group B is “kids who chose not to go to school an hour earlier”. I would be very surprised if group A didn’t do better in school, given that they’re being selected for motivation/not being tired/etc.
Anyway, I still found this useful and don’t want to be negative; just thoughts on what would make it even better for me in the future.
Thanks for your feedback, in fact correlation is not causation and we must be very careful about self-selection effects. This is not a self-selection effect but still a correlation/causation enigma that I found interesting in recent times: high vitamin D levels were found to be heavily anticorrelated with severe COVID in observational studies, but people of old age are both sensible to severe COVID and have lower vitamin D than average, not only that but people with a healthy lifestyle of many outdoor walks also have higher vitamin D! Is this causation, correlation or both? There is a very interesting article about this on Astral Codex 10 (COVID/Vitamin D, Much More Than You Wanted To Know)
Thanks for writing this!
Something you might want to consider in the future is going into the claims made by the book slightly more. While I was reading this, I found myself constantly thinking “Yeah, but should I trust this study?”. It sounds like you’ve looked into this and find them convincing, but I personally would have found it useful to include a little bit more information, like “How big was the study?”, “Was it observational or experimental?”, “Has anyone reproduced the results?”.
The part I was most skeptical of is:
It sounds like there’s a pretty major confounder here if group A is “kids who chose to go to school an hour earlier” and group B is “kids who chose not to go to school an hour earlier”. I would be very surprised if group A didn’t do better in school, given that they’re being selected for motivation/not being tired/etc.
Anyway, I still found this useful and don’t want to be negative; just thoughts on what would make it even better for me in the future.
Thanks for your feedback, in fact correlation is not causation and we must be very careful about self-selection effects. This is not a self-selection effect but still a correlation/causation enigma that I found interesting in recent times: high vitamin D levels were found to be heavily anticorrelated with severe COVID in observational studies, but people of old age are both sensible to severe COVID and have lower vitamin D than average, not only that but people with a healthy lifestyle of many outdoor walks also have higher vitamin D! Is this causation, correlation or both? There is a very interesting article about this on Astral Codex 10 (COVID/Vitamin D, Much More Than You Wanted To Know)