A. Measure Types

This page contains an overview of the measure types available in sampling packages; both packages that are are built-in to the carp_mobile_sensing framework, as well as the external ones. This list is constantly evolving as we release more and more support.

Measure Type Format

The dataType of a Measure specify what type of data to collect. This string version of this DataType is typically on the "namespace" + "name" format, where the namespace typically is dk.cachet.carp and the name is the measure type:

  dk.cachet.carp.<type>

The type is specified in the tables below.

Event-based vs. One-Time Measures

Most measures are event-based (EB), i.e., once triggered they continuously sample data from its sensor. For example, collecting a step count event every time a step is detected on the phone. However, some measures are one-time (OT), i.e. sampling one piece of data when triggered. For example, collecting location data.

It is important to know the type (EB vs. OT) of a measure since an event-based measure can be started and run until stopped, whereas a one-time measure needs to be triggered in order to sample data. This can, for example, be done periodically using appropriate triggers, like the PeriodicTrigger.

The difference when specifying the study protocol is illustrated below. The first task added to the protocol contains a one-time measure (device info) which is triggered only once. The second task contains a set of event-based measures that are triggered to start immediately and keep sampling data based on events. The third task collects location (one-time measure) periodically every 5 minutes.

  // Collect device info only once, when this study is deployed.
  protocol.addTaskControl(
    OneTimeTrigger(),
    BackgroundTask(
        measures: [Measure(type: DeviceSamplingPackage.DEVICE_INFORMATION)]),
    phone,
  );

  // Immediately start collecting step count, ambient light, screen activity, and
  // battery level events. Alle event-based measures.
  protocol.addTaskControl(
    ImmediateTrigger(),
    BackgroundTask(measures: [
      Measure(type: SensorSamplingPackage.STEP_COUNT),
      Measure(type: SensorSamplingPackage.AMBIENT_LIGHT),
      Measure(type: DeviceSamplingPackage.SCREEN_EVENT),
      Measure(type: DeviceSamplingPackage.BATTERY_STATE),
    ]),
    phone,
  );

  // Add a background task that collects location regularly
  protocol.addTaskControl(
    PeriodicTrigger(period: Duration(minutes: 5)),
    BackgroundTask(measures: [
      (Measure(type: ContextSamplingPackage.CURRENT_LOCATION)),
    ]),
    locationService);

Each SamplingPackage provides a list of what types of measures it supports using the dataTypes property. Each sampling package also comes with a default sampling schema for each of its measure types (if needed).

Available Measure Types

CAMS comes with a large set of predefined measure types, each available in different sampling packages. Some measures are part of CAMS, others are available in separate sampling packages, and some are part of device-specific sampling packages.

The tables below describe for each measure:

• Type Name - all type names are of the format dk.cachet.carp.<type>, where type is listed below
• Availability on Android and/or iOS
• The sampling package containing the measure
• Type of measure - event-based or one-time
• The Data type collected from this measure
• A description

Built-in Sampling Packages

Type	Android	iOS	Package	OT/EB	Data	Description
acceleration	+	+	sensors	EB	Acceleration	Rate of change in velocity in x, y, z - including gravity.
nongravitational acceleration	+	+	sensors	EB	Acceleration	Rate of change in velocity in x, y, z, - excluding gravity,.
acceleration features	+	+	sensors	EB	Acceleration Features	Acceleration events over a specific sampling period and calculates higher-order features.
rotation	+	+	sensors	EB	Rotation	Rotation of the device in x, y, z (typically measured by a gyroscope).
magneticfield	+	+	sensors	EB	MagneticField	Magnetic field around the device in x,y,z (typically measured by a magnetometer).
stepcount	+	+	sensors	EB	StepCount	Step count events since last system reboot from the device on-board sensor.
ambientlight	+	-	sensors	EB	AmbientLight	Ambient light from the phone's front light sensor.
device information	+	+	device	OT	Device Information	Basic device information.
batterystate	+	+	device	EB	BatteryState	Battery charging status and battery level.
screenevent	+	-	device	EB	ScreenEvent	Screen events (on/off/unlock).
freememory	+	-	device	EB	FreeMemory	Free memory.
timezone	+	+	device	OT	Timezone	Timezone of the device.

External Sampling Packages

Type	Android	iOS	Package	OT/EB	Description
currentlocation	+	+	context	OT	Request the current location of the phone.
location	+	+	context	EB	Listens to the stream of location changes from the phone's OS.
activity	+	+	context	EB	Activity as recognized by OS.
weather	+	+	context	OT	Local weather and weather forecast of the current location of the phone
air_quality	+	+	context	OT	Air quality of the current location of the phone (from land-based stations)
geofence	+	+	context	EB	Tracking entry, dwell, and exit event in circular geofences
mobility	+	+	context	EB	Track location and calculates mobility features based on the mobility_features plugin.
bluetooth	+	+	connectivity	EB	Scanning nearby bluetooth devices.
wifi	+	+*	connectivity	EB	Collects SSID and BSSID from connected wifi networks.
connectivity	+	+	connectivity	EB	Connectivity status events.
audio	+	+	media	OT	Records audio from the device microphone.
noise	+	+	media	EB	Detects ambient noise from the device microphone.
phonelog	+	-	communication	OT	Log of phone calls in/out.
textmessagelog	+	-	communication	OT	Log of text messages (sms) in/out.
textmessage	+	-	communication	EB	Text message (sms) events when received.
calendar	+	+	communication	OT	Collects all calendar events from the calendars on the phone.
survey	+	+	survey	OT	Collects data from surveys (questionnaires) via the Research Package including cognitive assessments from the Cognition Package.
apps	+	-	apps	OT	List of installed apps.
appusage	+	-	apps	OT	List of app usage.

Notes:
 * : not available on iOS >= 13

Wearable Device Sampling Packages

Type	Android	iOS	Package	OT/EB	Description
health	+	+	health	OT	Collects different types of health data from Apple Health or Google Fit that may come from wearable devices.
movisens	+	-	movisens	EB	Activity and Heart Rate Monitoring using the Movisens Move4 and EcgMove4 devices.
esense	+	+	esense	EB	Inertial measurement unit (IMU) sensor events and button press/release events from the eSense device.
polar	+	+	polar	EB	Inertial measurement (accelerometer, gyroscope, magnetometer) and heart rate (ECG, PPI, PPG, HR) data from the Polar devices.
movesense	+	+	movesense	EB	State (tap), heart rate (HR), ECG, and Inertial Movement Unit (IMU - accelerometer, gyroscope, magnetometer) data from the Movesense devices.

Note that each of these device measures has sub-types, such as dk.cachet.carp.movisens.hr for heart rate (HR) measures from the Movisens device.