In healthcare services, the goal is to provide patients with the right care, in the right place, at the right time, every time. Achieving reliability in healthcare processes is crucial for ensuring consistent and high-quality care. But what exactly is reliability and how do we measure it?

What is reliability?

Reliability, as defined by Igor Ushakov in the Handbook of Reliability Engineering, is “the measurable capability of something to perform its intended function in the required time under specified conditions.” It is about quantifying how often a process is done right, with the aim of minimising errors and achieving consistent outcomes.

How do you do it?

To design effective and reliable processes, we must start with common agreement among the team on what the right process entails. This includes identifying the core elements that ensure quality and can be measured. Administrative and support processes, as well as equipment management, should also be considered within the scope of this common agreement. By using process mapping and developing protocol-based care, we can uncover differences in clinical practice and establish common agreements based on evidence-based care bundles.

Measuring the current reliability of a process is essential to understand its performance. The frequency at which a process is done correctly determines its reliability. Different levels of reliability are categorised based on the number of failures out of a given number of opportunities. For example, a basic level of reliability (10-1) represents 80 to 90% success, while a highly reliable level (10-4) signifies five failures or fewer out of 10,000 opportunities.

Once the current reliability is measured, the focus shifts to making improvements and continuously monitoring the reliability of the processes. This ongoing evaluation ensures that the desired level of reliability is maintained and any deviations or areas for improvement are identified.


NHS Design principles, inspired by the NHS Constitution, provide guidance for effective process design. These principles serve as a foundation for decision-making and help create processes that are patient-centered, efficient, and reliable. By aligning with these principles and implementing human-centred design approaches, healthcare teams can design processes that are effective, reliable, and ultimately enhance the quality of care.

The Chartered Institute of Ergonomics and Human Factors have written advice and guidance on the human-centred design of work procedures such as written instructions, checklists and flow charts. It outlines the key guidance points that designers of procedures should address at all stages of their development, implementation and review.

Case studies

Examples include developing a common language using NEWS (read case study), implementing a care bundle of evidence-based interventions in PERIPrem (read case study), and using a checklist to reduce the risk of overcrowding in Emergency Departments (read case study).