Evidence collection and analysis

We collect a range of evidence as part of our investigations, to help us understand concerns about patient safety and to produce our findings and safety recommendations.

Evidence collection

These are the sources of evidence that are usually included in our investigations:

  • Speaking with patient and families.
  • Speaking with NHS and healthcare staff.
  • Reviewing relevant medical records, local policies and incident reports.
  • Observation visits to understand how healthcare is delivered in practice.
  • Reviewing academic and professional literature.
  • Speaking with national organisations and reviewing national policies.
  • Speaking with or working alongside subject matter experts, including healthcare and non-healthcare professionals, and patients or patient groups.


We analyse our evidence using a range of methods that adopt a human factors and ergonomics approach (sometimes referred to as ‘safety science’). Human factors is an established scientific discipline used in many other safety critical industries, such as aviation, rail transport and nuclear power stations.

Methods and tools

We use practical and academic models and tools to help us better understand how patient safety incidents occur. This allows us to adopt a systems perspective that does not find blame or liability with individuals or organisations.

Common methods and tools used in our investigations to help develop our findings and safety recommendations include:

  • The Systems Engineering Initiative for Patient Safety (SEIPS).
  • AcciMap.
  • ATSB investigation analysis model.
  • Functional Resonance Analysis Method.
  • Thematic analysis.
  • Bow Tie analysis.
  • Hierarchical Task Analysis (HTA).
  • Systems-Theoretic Accident Mode and Processes/Systems-Theoretic Process Analysis (STAMP/STPA).
  • The hierarchy of controls.
  • The hierarchy of intervention effectiveness.

Our investigation reports include information on the specific methods we have used to collect and analyse our evidence.

Check and challenge

The organisations and contacts we have made are listed in our investigation reports to demonstrate the range of views we have taken within a specific investigation.

As part of our consultation process we share the report with a range of national stakeholders on consultation before we publish our final report. Our reports do not name individuals or local healthcare organisations but such sharing allows for further check and challenge of evidence and findings that would be included in our final report, including by patient and family representative groups.

The national stakeholders we regularly consult includes:

  • NHS England
  • the Care Quality Commission
  • the Medicines and Healthcare products Regulatory Agency
  • the Parliamentary and Health Service Ombudsman
  • Royal colleges
  • patient and family representative groups.

Subject matter advisors

It’s important that our investigations are informed by expert opinion. This helps us better understand patient safety concerns and allows us to produce robust findings, safety recommendations and other safety learning.

Our investigations always speak with patients, families, healthcare staff and national organisations to take evidence and gain insight across multiple groups and help us check and challenge our investigations from different perspectives.

Sometimes we also identify the need for more specific subject matter advice to help us gain additional knowledge and insight into a specific patient safety concern. We can identify subject matter advisors in several ways, including engagement with professional bodies, academic institutions, voluntary and charitable groups, or other national organisations.

Subject matter advisors may include:

  • Experts by lived experience, where people with direct experiences of care can help us better understand the patient and family perspective.
  • Healthcare professions, where experienced staff can help inform us about certain conditions, procedures, or ways of working.
  • Non-healthcare professionals, where we may need additional experience to help us understand areas outside of healthcare such as product design or engineering.
  • Academic and human factors professionals, where we may need additional support to understand academic work or assistance to apply cutting edge safety science.

When a designated subject matter advisor contributes to a patient safety investigation this is stated in our investigation report and they are also bound by the legal requirement of protected disclosure.