Table 1.

Suggested labels given phone-usage level and activity level and their real-life implications.

Device Usage	Number of Uploads	Implication	Prototype Label
High	High	Engaging with the device	Non-Missing
High	Low	Using the device but inactive	N/A
Low	High	Active, carrying/wearing the device but not engaging	N/A
Low	Low	Not engaged and not carrying/wearing the device	Missing