What is it? Why is it important?

The study design is the overall strategy used to integrate all different study components needed to answer a study question.


Many study designs exist but most can be divided into:

  • Exploratory research designs: used to investigate a problem that is not clearly defined
  • Observational research designs: observe and describe a situation without influencing its outcome
  • Causal research designs: evaluate the impact of a specific change on existing norms and assumptions


The aim and complexity of a study can affect the choice of study design that must be implemented. The use of a study design does again significantly affect:

  • Resources and expertise required
  • Number of required participants
  • Time needed to complete the study
  • Budget, as more procedures, staff, trainings, including data collection procedures become necessary

What do I need to do?

The study must be operationally feasible. As a SP-INV select the least complex study design needed to answer your study question:

  • Avoid unnecessary complexity and procedures
  • Ensure study documents are clear, concise, and consistent
  • Ensure that collected data, whether based on an electronic- or paper CRF reflect specifications given in the study protocol
  • Select the minimum of required variables to answer your study question


Only variables contributing to the answer of your study question will be useful. Collection based on "nice to have" rather than data needed to answer the study question will only increase study complexity and resources, and finally the study budget.


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

  • 5.4 Trial design


ICH Topic E9 Statistical principles for clinical trials - see in particular guideline

  • 3 Trial design consideration


ICH Topic E8 (R1) General considerations for clinical studies – see in particular guideline

  • 2.2 Scientific approach in design and analysis


ISO 14155:2020 Medical devices (access liable to costs) - see in particular section

  • 6.3 Justification for the design
  • CTU – Clinical Trials Unit
  • eCRF – electronic Case Report Form
  • ICH – International Council for Harmonisation
  • ICH GCP – International Council for Harmonisation - Good Clinical Practice
  • ISO – International Organization for Standardization
  • pCRF – paper Case Report Form
  • SP-INV – Sponsor Investigator
Concept ↦ Management ↦ Study Idea ↦ Design

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 ↦ Management ↦ Study Idea ↦ Design

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