Is server time always more accurate?

It is useful for receipt timing but does not itself demonstrate when the participant completed the response.

Can a clock offset be corrected later?

A derived correction may be considered when reliable evidence supports it; retain the original value and remaining uncertainty.

ePRO Device Clocks: Separating Response Time from Receipt Time

Published: 28 October 2026
Updated: 28 October 2026

The moment an electronic participant report reaches a server may differ from the moment it was completed. Offline use or an incorrect device clock can cause reviewers to misinterpret whether a response met its intended timing window.

Preserve the meaning of data

Define which timestamps are retained and what each represents. Device time, time zone, server receipt and known clock offsets may be separate fields. Assess the limitations of a clock that users can change. Technical time controls alone do not resolve scientific questions about delayed entry, recall or the suitability of an observation for analysis.

Worked example

For example, a participant completes a questionnaire while travelling and submits it after finding connectivity. Server receipt suggests that the response occurred outside the intended window. Reviewers examine response and delivery times together. If the device clock is unreliable, they retain that uncertainty and document the reason for the data-review decision.

Review checks

Test offline completion together with delayed delivery.
Assess how device-clock changes affect existing and new records.
Identify the timestamp used by a report in its label or explanation.

Acceptance and boundaries

Acceptance means a reviewer can distinguish collection time from receipt time. Suspicious timestamps should neither be accepted automatically nor cause every record to be rejected. Assess their effect against the study purpose and predefined review approach. If a correction is justified, preserve the original timestamp and the rationale so the decision can be reconstructed.

Frequently asked questions

Is server time always more accurate?: It is useful for receipt timing but does not itself demonstrate when the participant completed the response.
Can a clock offset be corrected later?: A derived correction may be considered when reliable evidence supports it; retain the original value and remaining uncertainty.