What is it? Why is it important?

Source Data (SD) is the original data derived from some primary source (e.g. lab report, participant questionnaire, medical examinations).

SD originate from:

  • Information on participants based on existing medical records (e.g. medical history such as lab-, x-ray reports)
  • Study specific information (e.g. study specific medical examinations, participant diaries and questionnaires)

Source data:

  • Is information needed in order to answer the study question
  • Must be clearly documented and defined in the study protocol
  • Are entered in the CRF eventually used for the statistical analysis of the study


Handling of SD is strictly regulated:

  • The protocol describes the study and any SD needed to answer the study question
    • Once approved by the EC/RA only SD listed and described in the study protocol can be collected and used in the study.
    • Adding additional SD, not specified in the study protocol, requires an amendment and prior EC/RA approval
  • SD should be attributable, legible, contemporaneous, original, accurate, and complete (ALCOAC)
  • Changes to SD must be traceable, must not obscure the original entry, and must be explained if necessary (e.g. via an audit trail that documents what changes were made by who at what time)
  • Any SD copies must be certified and follow a pre-defined certification process
  • Direct access to SD must be guaranteed during study monitoring, audits, EC review, and regulatory inspection(s)

What do I need to do?

Based on the protocol, make a list and:

  • Define required SD needed to answer the study question.
  • Give a description of its variable(s) (e.g. vital scores, scales, various parameters)
  • Define how variables should be specified (e.g. mg/ml, ml/sec., as a sum score, based on formula)
  • Provide the source where SD is originally recorded (e.g. questionnaire, medical record, lab reports, patient diary, notes)
  • Provide location where collected SD is stored (e.g. patient or study file)


For more information refer to Documents in this Study Guide.

Where can I get help?

Your local CTU can support you with experienced staff regarding this topic


ICH GCP E6(R2) – see in particular guidelines

  • 1.51 Source documents definition
  • 4.9.0 Records and Reports
  • 6.10 Direct Access to Source Data / Documents

ISO 14155:2020 Medical devices (access liable to cost) - see in particular sections

  • 7.5.3 Source documents
  • 7.8 Document and data control
  • g Monitoring
  • ALCOAC - Attributable Legible Contemporaneous Original Accurate, Complete
  • CRF – Case Report Form
  • CTU – Clinical Trials Unit
  • EC – Ethics Committee
  • EC/RA – Ethics committee / Regulatory Authorities
  • ICH-GCP – International Council for Harmonisation - Good Clinical Practice
  • ISO – International Organization for Standardization
  • SD – Source Data
Development ↦ Management ↦ Study Documents ↦ Source Data

Provides some background knowledge and basic definitions

Basic Protocol
Basic Statistics
Basic Monitoring
Basic Drug or Device

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Protocol
Concept Statistics
Concept Drug or Device

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Protocol
Development Statistics
Development Drug or Device

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Protocol
Set-Up Ethics and Laws
Set-Up Statistics
Set-Up Quality and Risk
Set-Up Drug or Device

Starts with participant recruitment

Ends after the last participant has completed the last study visit

Conduct Protocol
Conduct Statistics
Conduct Drug or Device

Starts with last study visit completed

Ends after study publication and archiving

Completion Protocol
Completion Statistics
Completion Drug or Device
Current Path (click to copy): Development ↦ Management ↦ Study Documents ↦ Source Data

Please note: the Easy-GCS tool is currently under construction.