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. 2022 Nov 18;4:964582. doi: 10.3389/fdgth.2022.964582

Table 1.

Features extracted from the passively collected MAIKI data.

Feature type Name Description
GPS Location variance The logarithm of the sum of the statistical variances in the latitude and the longitude of all GPS coordinates in the day
Location entropy The variability of the time that participants spend in significant places in the day
Normalised location entropy The location entropy divided by the logarithm of the number of significant places
Time at home Home is defined as the most frequent significant place where a participant spent the most time between 0 to 6 am; time at home is defined as the percentage of time a participant spent at home relative to other significant places
Total distance The total distance covered by a participant during the day
Communication Total calling frequency The number of times that a participant answers and makes phone calls during a day
Total calling duration The total time in minutes that a participant spends each day answering and making phone calls (in min)
Non-working time calling frequency The number of times that a participant answers and makes phone calls at times other than 8 to 6 pm during a day
Non-working time calling duration The total time that a participant answers and makes phone calls at times other than 8 to 6 pm during the day (in min)
Number of missed calls The number of calls that are marked as missed during the day
Number of contacts The number of contacts a participant answers and makes phone calls during the day
Calling entropy The variability of calling durations a participant spends in contacts during the day
Normalised calling entropy Calling entropy divided by the logarithm of the number of contacts during the day
Phone usage Phone usage frequency The number of times that a participant interacts with their phone during a day
Phone usage duration The total time in minutes that participants spend each day interacting with their mobile phones
User activity Lock screen duration The total time in minutes that participants lock their mobile phones during the day
Number of used apps The number of applications that a participant uses during the day
Midnight app usage The number of applications that a participant uses between 0 to 5 am during the day
Sleep time Sleep time [min] is considered to be between the last time an app was used in the previous day (or in the same day before 2 am if available) and the first time an app was used after 5 am

Four types of features have been derived: GPS, communication, phone usage as well as user activity features.