ojwalch
commented
9 months ago Hey Scott— thanks! That's gravity. (Take the square root of ax^2 + ay^2 + az^2 and you'll get something pretty close to 1 whenever someone's not moving. That's the 1 of 1g, which is the gravity the watch is experiencing.)
On Feb 6, 2024, at 12:25 AM, Scott Linderman @.***> wrote:
Thanks for putting together this dataset! I'm considering using it for a homework assignment in my applied statistics class. I have a basic question about the acceleration data. I must be missing something obvious...
Looking at fig. 1 of your paper https://academic.oup.com/sleep/article/42/12/zsz180/5549536 I see long stretches where the acceleration is non-zero. How should that be interpreted? The watch can't be undergoing constant acceleration because it would fly off to outer space, right? Is this some quirk of the MEMS accelerometer, or is there some counteracting force that isn't reported in these measurements?
image.png (view on web) https://github.com/ojwalch/sleep_classifiers/assets/5632040/3e1b560b-1d70-474d-bdc1-341b10d8c573
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slinderman
Thanks for putting together this dataset! I'm considering using it for a homework assignment in my applied statistics class. I have a basic question about the acceleration data. I must be missing something obvious...
Looking at fig. 1 of your paper I see long stretches where the acceleration is non-zero. How should that be interpreted? The watch can't be undergoing constant acceleration because it would fly off to outer space, right? Is this some quirk of the MEMS accelerometer, or is there some counteracting force that isn't reported in these measurements?