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WHO-5 and experience sampling, alongside wearable data

Sensors measure the body; people report how they feel. ATS-1 pairs the two, using self-report as an anchor and never as a diagnosis.

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Article · Reviewed 5 November 2026

Why pair sensors with self-report

Passive signals such as sleep and HRV show what the body did. They do not show how the person felt. Self-report fills that gap and lets teams check whether a sensor-based change matched an experienced one.

The WHO-5 in brief

The WHO-5 asks five questions about how a person has felt over the last two weeks, each answered from 0 ("at no time") to 5 ("all of the time"). The raw score is the total, from 0 to 25; multiplied by 4, it gives a percentage score from 0 to 100 (WHO-5 questionnaire and scoring (WHO Regional Office for Europe, 1998)). It has been widely studied (Topp et al., 2015, systematic review of the WHO-5).

Published WHO-5 literature includes cut-offs used for screening. Screening is outside ATS-1's scope, so ATS-1 shows the score without cut-offs.

Experience sampling

Experience sampling, also called ecological momentary assessment, asks people brief questions several times a day in daily life, reducing reliance on memory (Myin-Germeys et al., 2018, World Psychiatry). Its design choices decide both data quality and participant burden.

ATS-1 sampling defaults

ATS-1 self-report defaults
SettingATS-1 default
Prompt scheduleSignal-contingent, semi-random: 6 prompts a day in a 12-hour window
Expiry20 minutes
Burst lengthAt least 6 days
ComplianceTarget at least 80%; participants below 33% are excluded from index computation and reported
WHO-5Every 14 days

Aligning self-report with sensor data

  • Store every answer with its timestamp and timezone
  • Compare daily affect with the night before and the day itself, not a weekly average
  • Represent surveys as subjective reports; see IEEE 1752.1 and Open mHealth
  • Report compliance alongside every result

What this guide does not claim

ATS-1 is for research and general wellness only. It does not diagnose, treat, prevent or predict any disease, including any mental health condition. For questions about your own health, speak to a healthcare professional.

Questions

Is the WHO-5 free to use?

The WHO-5 is widely described as free to use. Check the terms of the version and translation you use before you deploy it in a product.

Why no cut-offs?

Cut-offs are for screening. ATS-1 is a research and general-wellness specification, so it shows scores and changes, never a screening result.

Sources

  1. WHO-5 questionnaire and scoring (WHO Regional Office for Europe, 1998)
  2. Topp et al., 2015, systematic review of the WHO-5
  3. Myin-Germeys et al., 2018, World Psychiatry

Keep reading

Plane methodsHow ATS-1 collects each plane: nightly lnRMSSD, sleep timing, provenance, IEEE 1752.1 mapping, WHO-5 every 14 days and sampling rules.State IndexThe ATS-1 State Index: robust z-scores of HRV, sleep and affect against a 28-day personal baseline, using the median and MAD.IEEE 1752.1 and Open mHealthWhat IEEE 1752.1-2021 standardizes, how Open mHealth schemas relate to it, where HRV sits, and how ATS-1 maps Plane I data to it.Personal baseline methodsHow to build a personal baseline from wearable data: window length, warm-up, robust statistics, missing data, device changes and honest reporting.

Take the next step.

How the WHO-5 is scored, how experience sampling works, and how to align self-report with wearable data, without cut-offs or screening claims.

Get the textbook Plane methods