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CARP Documentation

What is CARP?

CARP (Copenhagen Research Platform) is a free, open-source toolkit for collecting data from phones and wearables. New here? The home page has the short version and a video.

For example, imagine a researcher who wants to know how sleep affects mood. They need an app that quietly counts steps, notices when the phone screen turns on at night, and asks the participant “How do you feel today?” every morning. Then all that data must end up somewhere safe where the researcher can analyse it.

Building all of that from scratch takes months. CARP gives you the building blocks so you can do it in days.

What can CARP collect?

Section titled “What can CARP collect?”

Phone sensors

Steps, location, activity (walking, running, still), screen on/off (Android), battery, light, noise.

Wearables

Heart rate and more from devices like Apple Watch, Polar and Movesense.

Questions

Surveys and questionnaires the participant fills in, plus small cognitive tests.

Health apps

Data already stored in Apple Health or Google Health Connect.

The three parts of CARP

Section titled “The three parts of CARP”

You only need to remember three things:

flowchart LR
    A["<b>Study protocol</b><br/>the recipe:<br/>what to collect and when"] --> B["<b>The app</b><br/>follows the recipe<br/>on the phone"]
    B --> C["<b>Storage</b><br/>where the data ends up"]
  1. The study protocol is a recipe. It says “collect steps and screen events, all the time” or “ask this survey every morning at 8:00”.
  2. The app runs on the participant’s phone. It reads the recipe and does the collecting. The part of CARP that does this is called CARP Mobile Sensing (you’ll see it shortened to CAMS).
  3. Storage is where the data goes: kept on the phone, sent to CARP’s own server (CAWS), or sent to a server you already have.

That’s the whole idea. Everything else in these docs is detail.

How you start

Section titled “How you start”

Every study follows the same two steps:

  1. Configure your study: the protocol (what to collect, from which device, and when), the consent and the translations.
  2. Run your study in the ready-made CARP Studies app: first on your own phone, then with participants.

No app code is needed. If you later need a new data type, your own server or your own app, see Make it your own.