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Welcome to the Understanding America – American Life in Realtime (ALiR) study!

This page provides links to documents and data from the Understanding America Study's American Life in Realtime (ALiR) Study. The goal of ALiR is to use activity trackers to understand how day-to-day activity and sleep behaviors relate to physical and mental health in a representative sample of Americans.

This study began in August of 2021 with a nationally representative sample of 1,038 UAS members who were provided with Fitbit inspire 2 devices and were followed over the course of one year. Since then, we have allowed members to continue to contribute Fitbit data for as long as they wish to participate. In addition, we have continued to add additional participants and devices (e.g., Apple Watch).

To date, we have collected over 400 million minutes (~300,000 days) of activity tracker data across ~1,500 unique participants.
Currently there are around 1500 active members, though this is expected to grow to over 10,000 over the next few years.



ALiR’s documentation and datafiles are currently available for research use by inquiry. Please contact ALiR study director, Dr. Ritika Chaturvedi @ ritikac@usc.edu.

Data elements include (Table 1):

  • Baseline surveys.
  • Monthly repeated surveys.
  • Fitbit’s provided daily data summaries (general Use Tier): activity, steps, sleep, heart rate (HR), heart rate variability (HRV), SpO2, temperature, basal metabolic rate (BMR).
  • Derived data summaries by UAS’s inhouse analytics team (general use tier): walking speed, gait, circadian rhythm, device wear patterns.
  • Fitbit’s raw intraday (minute level) data (restricted tier): activity, steps, sleep, HR, HRV, SpO2, temperature, BMR.
Table 1: ALiR’s Individual-level Data (not exhaustive).


ALiR’s documentation and datafiles are currently available for research use by inquiry. Please contact ALiR study director, Dr. Ritika Chaturvedi @ ritikac@usc.edu.


USC Press Release July 28, 2020

Partner Evidation Health's Press Release


The first wave of funding was made possible by a grant from the National Library of Medicine, R01LM013237, "Large-Scale Nationally Representative Person-Generated Health Data for Development of Generalizable Data Science Methodologies for Precision Public Health."

The team is lead by Ritika Chaturvedi, with UAS team members:

Marco Angrisani
Arie Kapteyn
Bas Weerman
Eva Ortega
Brett Jordan
Tania Gutsche
and past partner was Monika Jain of Evidation Health, who managed the first wave of ALiR on their platform.