What is it? Why is it important?

The statistician works in collaboration with the SP-INV to decide on a suitable study design able to answer the study question.


Responsibilities include to:

  • Write the Statistical Analysis Plan (SAP), which includes to define
    • Required sample size
    • Outcome measures
    • Applicable statistical methods
    • Requirement for interim analysis
    • Randomisation procedures
    • Format and frequency of data exports
  • Elaborate the randomisation list to be implemented in the study
  • Write the statistical section of the study protocol
  • Perform the statistical analysis of the study and write the statistical study report
  • Support the SP-INV in interpreting statistical information in order for the SP-INV to draw conclusions and make predictions

What do I need to do?

As a SP-INV, establish a requirement profile for a statistician. A qualified statistician can help you to answer important questions such as:

  • Can the study hypotheses be answered statistically?
  • Are the selected study endpoints able to answer the study question?
  • Based on study design what sample size would be required to ensure statistical power?
  • What statistical analysis plan would best-fit-for-purpose
  • Based on required sample size, is the access to local participants adequate or is an expansion to a multi-centre study required?


Based on your research question, the statistician will be able to suggest the most appropriate study design and statistical method(s) needed to provide a useful answer.


For more information refer to Statistics 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 guideline

  • 6.9 Statistics
  • CTU – Clinical Trials Unit
  • ICH GCP – International Council for Harmonisation - Good Clinical Practice
  • SAP – Statistical Analysis Plan
  • SP-INV – Sponsor-Investigator
Concept ↦ Data Handling ↦ Stakeholders ↦ Statistician

Provides some background knowledge and basic definitions

Basic Monitoring
Basic Drug or Device

Starts with a study idea

Ends after having assessed and evaluated study feasibility

Concept Drug or Device

Starts with confidence that the study is feasible

Ends after having received ethics and regulatory approval

Development Drug or Device

Starts with ethics and regulatory approval

Ends after successful study initiation

Set-Up Ethics and Laws
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 Drug or Device

Starts with last study visit completed

Ends after study publication and archiving

Completion Statistics
Completion Drug or Device
Current Path (click to copy): Concept ↦ Data Handling ↦ Stakeholders ↦ Statistician

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