Table 2.
Predictive features used in each of the models.
| Devicea and category | Features | |
| Fitbit | ||
|
|
Subject features | Gender, age, height, weight, and sitting heart rate |
|
|
Acceleration features | Steps features: |
|
|
steps mean, steps difference (t-1, t-2, t-3, t-4, and t-5 minutes); steps mean and SD of last 5 minutes | |
|
|
Physiological features | Fitbit heart rate features: |
|
|
Fitbit heart rate above sitting heart rate, Fitbit heart rate percentage of maximum heart rate, Fitbit heart rate mean, Fitbit heart rate difference (t-1, t-2, t-3, t-4, and t-5 minutes), and Fitbit heart rate mean and SD of last 5 minutes | |
| ActiGraph | ||
|
|
Subject features | Gender, age, height, and weight |
|
|
Acceleration features | X, Y, Z features: minimum, maximum, mean, SD; median crossings; 10th, 25th, 50th, 75th, 90th percentiles; correlations (XY, XZ, YZ); dominant frequency; dominant frequency magnitude First order differential of X, Y, Z features: minimum, maximum, mean, SD; median crossings; 10th, 25th, 50th, 75th, and 90th percentiles; correlations (XY, XZ, YZ); dominant frequency; dominant frequency magnitude Vector magnitude features: vector magnitude mean; vector magnitude difference (t-1, t-2, t-3, t-4, and t-5 minutes); vector magnitude mean and SD of last 5 minutes |
|
|
Physiological features | Polar heart rate features: polar heart rate above sitting heart rate; polar heart rate percentage of maximum heart rate; polar heart rate mean; polar heart rate difference (t-1, t-2, t-3, t-4, and t-5 minutes); polar heart rate mean and SD of last 5 minutes |
| SenseWear | ||
|
|
Subject features | Gender, age, height, and weight |
|
|
Acceleration features | X, Y, Z features: peaks, mean of absolute differences, average; Steps features: steps mean; steps difference (t-1, t-2, t-3, t-4, and t-5 minutes); steps mean and SD of last 5 minutes |
|
|
Physiological features | Polar heart rate features: polar heart rate above sitting heart rate; polar heart rate percentage of maximum heart rate; polar heart rate mean; polar heart rate difference (t-1, t-2, t-3, t-4, and t-5 minutes); polar heart rate mean and SD of last 5 minutes; and SenseWear sensors: near body temperature average, Galvanic skin response average, skin temperature average |
aFor each device, the subject characteristics, acceleration features, and physiological features are listed.