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MESA Actigraphy "Activity"

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dpanesar +0 points · about 2 months ago

Hi,

I am currently looking through the MESA Actigraphy data and needed some clarification on some of the variables.

Specifically, the Activity Variable which is supposed to the be the activity count.

Is this variable by chance a ZCM (zero-crossing method) or PMI (process machine interaction) score derived from the accelerometer activity form the actigraph band? If neither where is the count derived from and what are the units etc.? Would it be possible to get ZCM or PMI or a similar variable perhaps through analyses etc.?

Thank-you in advance for your assistance.

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mrueschman +0 points · about 1 month ago

I suggest reading more in the literature about the device used in MESA, the Actiwatch Spectrum. I did find this link, https://www.labfront.com/article/comparing-motionlogger-with-actiwatch-2, which suggests the Philips Actiwatch-2 (a precursor to the Spectrum) used proportional-integrating mode (PIM).

The Philips devices output the data in a single format, so to my knowledge it's not possible to go back and re-output/re-derive the watch data using other methods (e.g., ZCM).

Thanks for using the site!

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dpanesar +0 points · about 1 month ago

Perfect! Thankyou for your assistance.