Table 4.

Feature vector used to describe an activity.

Category	Feature	Description
Ambient sensor	Duration	Length of the activity in time
	NumSensorEvents	Number of sensor readings that were generated during activity
	NumSensors	Number of different ambient sensors (total) that generated readings
	NumMSensors	Number of motion sensors that generated readings
	NumDSensors	Number of door sensors that generated readings
	NumISensors	Number of item (vibration) sensors that generated readings
	NumIrrSensorEvents	Number of sensor readings from irrelevant sensors for this activity
	NumIrr Sensors	Number of different irrelevant sensors that generated readings
Wearable sensor (defined for each wearable sensor feature s and each possible sensor value si∈S)	Max	Maximum value for this feature
	Min	Minimum value for this feature
	Sum	Sum of the values, ${\sum }_{i=1}^N{s}_i$
	Mean	Mean of the values, s̄ = Sum(S)/N
	Median	Median of the values
	Standard Deviation	Standard deviation, $\sigma =\sqrt{\frac{1}{N}{\sum }_{i=1}^N{(s_i-\mu )}^2}$
	MeanAbs Dev	Mean absolute deviation, $\frac{1}{N}{\sum }_{i=1}^N\mid s_i-\overline{s}\mid$
	MedianAbsDev	Median absolute deviation, $\frac{1}{N}{\sum }_{i=1}^N\mid s_i-\mathit{Median}(S)\mid$
	Coeff Variation	Coefficient of variation, σ/μ
	Skewness	Asymmetry in the value distribution, $\frac{1}{N}{\sum }_{i=1}^N{(s_i-\mu )}^3/{(\frac{1}{N}{\sum }_{i=1}^N{(s_i-\mu )}^2)}^{\frac{3}{2}}$
	Kurtosis	The shape of the value distribution, $(\frac{1}{N}{\sum }_{i=1}^N{(s_i-\mu )}^4/{(\frac{1}{N}{\sum }_{i=1}^N{(s_i-\mu )}^2)}^3)-3$
	Signal Energy	Signal energy, ${\sum }_{i=1}^N{s}_i^2$
	LogSignal Energy	${\sum }_{i=1}^{N}log(s_i^2)$
	Power	Average energy, $\frac{1}{N}{\sum }_{i=1}^N{s}_i^2$
	SMA	Signal magnitude area for accelerometer/gyroscope axes, ${\sum }_{i=1}^N(\mid x_i\mid +\mid y_i\mid +\mid z_i\mid )$
	AutoCorrelation	Amount of correlation between the values at times t and t+1, ${\sum }_{i=1}^{N-1}(s_i-\overline{s})(s_{i+1}-\overline{s})/{\sum }_{i=1}^N{(s_i-\overline{s})}^2$
	Axis Correlation	Correlation between each pair of accelerometer/gyroscope axes S and ${\sum }_{i=1}^N(s_i-\overline{s})(v_i-\overline{v})/\sqrt{{\sum }_{i=1}^N{(s_i-\overline{s})}^2{\sum }_{i=1}^N{(v_i-\overline{v})}^2}$
Day Out Task	Magazine Count	Binary value indicating whether magazine subtask was performed
	HeatingPadCount	Binary value indicating whether heating pad subtask was performed
	MedCount	Binary value indicating whether medicine subtask was performed
	BusMap Count	Binary value indicating whether bus map subtask was performed
	Change Count	Binary value indicating whether change subtask was performed
	RecipeCount	Binary value indicating whether recipe subtask was performed
	PicnicBasketCount	Binary value indicating whether picnic basket subtask was performed
	ExitCount	Binary value indicating whether exit subtask was performed
	PValue	Number of different subtasks were interrupted at least once
	IValue	Maximum number of subtasks that were performed in parallel
	Task1	Subtask performed first
	Task2	Subtask performed second
	Task3	Subtask performed third
Participant	Age	Participant age
Activity	ActivityNum	Activity number