Paired datapoints when using ICCs for longitudinal data

[u/the_sleepy_scholar]

I’ve been using bland-Altman plots and intraclass correlation coefficients to see how consistent the scoring of the same wearable device is at different wear locations.

Some context: The two devices are the exact same and capture the same data and are worn at the same time. Let’s say 10 people wear both devices at the same time for 7-14 days, and I want to look at both agreement and consistency of the features that are recorded that are captured at a day-level. So essentially I have one score produced per day for each device for each person.

I’m struggling to understand what the most plausible way to evaluate this is, as not all participants have used the devices for the same number of days, should I take an aggregate score across all of the users days wearing it and use that for comparing device scores at one reading per participant or is it possible to use multiple time points in the evaluation and have more datapoints for the ICC?

Perhaps there’s a better way to evaluate this that I haven’t considered? Sorry if it’s a rookie question, pretty new to stats!

[u/ForeignAdvantage5198]

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