Comment by benrapscallion
2 years ago
That’s because this is in UK Biobank, a cohort of >500K Brits and collecting actually in such a large cohort is a miracle, let alone for multiple days. All thanks to the people who volunteered into the study. Would it be nice to have even more? Sure. But at that scale, patterns start to emerge.
An issue could be how people choose that week.
As you point out that's a multi day commitment, and if part of the volunteers either adjust the timing of the experiments to match specific weeks (e.g. parents choosing school vacations), or adjust their schedule accordingly, what is measured becomes fundamentally different in nature to what measuring longer periods would bring.
I'm with you on how we don't have a choice regarding to the quality of the study, it's just crazy hard to get any data at scale. But we can look at it as a very flawed "best of what we can do" and not take the patterns too seriously.
Note the study had 60977 samples, not >500K.
I was referring to the size of UK Biobank. Yes, only a fraction participated in actigraphy. The same is true of imaging, blood biomarkers, etc.
There’s a health research programme currently underway in the UK that’s looking to recruit up to 5 million people. I believe they’re currently at around the 1 million mark.
https://ourfuturehealth.org.uk/
I almost volunteered for this but was concerned that they were liberally using the NHS branding to disguise that they’re private
Yes. Any statistics buffs here who can tell me:
Is 500k brits for 1 week as good as 5k brits for 100 weeks.
Effectively with so much data aren't you getting a superposition anyway.
A superposition of?
In statistical mechanics there's a concept of "ensemble average" and its provable that if you have a system, the average state of the system over say a 100 realisations ("ensemble average") run for 1 second each, is equal to the the average of one system run for a 100 seconds - under some assumptions of course.
I don't know enough a about human biology to make a statement about whether any of those assumptions will hold true, but maybe someone else will.
I would also say it's geospecific. Like if there is a nationwide trauma of sorts (politics, etc) it could influence a group to not be representative of the population at large.
That's not the scenario here. An ensemble average requires those 1 second periods to be randomly sampled from the overall runtime. You can't just measure the first second after starting for all samples, or even the 7th second after starting, and say anything statistically sound about the average of the whole runtime.
The weeks that were measured in this study were not random. How far from random is the big question.
Humans age, so obviously not. Interesting analogy, though
I mean the data lacks any person's sleep history, but if there is a cohort of bad sleepers, as a group you get a collective pseudo-history (because altough study is done at the same time they are in different life stages) that is no-one's history but might track the average well for that cohort AND take into consideration more than a week.
In the similar way sampling the height of 1000 of 1M people will give you a good estimate of the average.
And that's fair - it should just thoroughly be discussed and qualified not to release false research.
How is this false research? Most other studies rely on self-reported measures of sleep. This is using objective measures.