Use error

The term Use Error has recently been introduced to replace the commonly-used terms human error and user error. The new term suggests that accidents should be attributed to circumstances, rather than to the human beings who happened to be there.

Definition

The term Use Error is defined in several international standards, such as IEC 62366, ISO_14155) and ISO_14971, to describe

an act or omission of an act that results in a different medical device response than intended by the manufacturer or expected by the user.

The need for the terminological change

Traditionally, human errors are considered as a special aspect of human factors. Accordingly, they are attributed to the human operator, or user. When taking this approach, we assume that the system design is perfect, and the only source for the use errors is the human operator. For example, the DoD HFACS classifies use errors attributed to the human operator, disregarding improper design and configuration setting, resulting in missing alarms, or in inappropriate alerting . The need for changing the term was because of a common mal-practice of the stakeholders (the responsible organizations, the authorities, journalists) in cases of accidents . Instead of investing in fixing the error-prone design, management attributed the error to the users. The need for the change has been pointed out by the accident investigators:

• Early in 1983, Hollnagel pointed out that the term Human Error refers to the outcome, not to the cause. A user action is typically classified as an error only if the results are painful
• In the story “Leap of Faith” of his book “Set Phasers on Stun”, Casey suggested that the acident of the Indian_Airlines_Flight_605 near Bangalor in 1990 could have been avoided, should the investigators of the Air_France_Flight_296 accident of 1988 past the Mulhouse-Habsheim airport considered the circumstances (exceptional situation), rather than the pilots (human errors).
• In his book “Managing the Risks of Organizational Accidents” (Organizational_models_of_accidents) Reason explained and demonstrated that often, the circumstances for accidents could have been controlled by the responsible organization, and not by the operators.
• In his book “The Field Guide to Understanding Human Errors” , Dekker argued that blaming the operators according to “The Old View” results in defensive behavior of operators, which hampers the efforts to learn from near-misses and from accidents.
• In a recent study by Harel and Weiss the authors suggested that the Zeelim accident during an Israeli military exercise in 1992 could have been prevented, should the Israeli forces focus on learning from the accident of 1990, rather than on punishing the field officers involved in the exercise.

Use errors and accountability

ISO standards about medical devices and procedures provide examples of use errors, which are attributed to human factors, include slips, lapses and mistakes. Practically, this means that they are attributed to the user, implying the user’s accountability. The FDA glossary of medical devices provides the following explanation about this term :

Safe and effective use of a medical device means that users do not make errors that lead to injury and they achieve the desired medical treatment. If safe and effective use is not achieved, use error has occurred. Why and how use error occurs is a human factors concern.

With this interpretation by ISO and the FDA, the term ‘use error’ is actually synonymous with ‘user error’. Another approach, which distinguishes ‘use errors’ from ‘user errors, is taken by IEC 62366. Annex A includes an explanation justifying the new term:

This International Standard uses the concept of use error. This term was chosen over the more commonly used term of “human error” because not all errors associated with the use of medical device are the result of oversight or carelessness of the part of the user of the medical device. Much more commonly, use errors are the direct result of poor user interface design

This explanation complies with “The New View”, which Dekker suggested as an alternative to “The Old View”. This interpretation favors investigations intended to understand the situation, rather than blaming the operators.

A proactive definition of use error

The ad-hoc definition implies that the use error is the consequence of a user command. This complies with the reactive approach to safety (Hazard_prevention), which might end up in a fatalistic attitude, implying that we cannot avoid use errors. The proactive approach, on the contrary, enable prevention of such mishaps, by considering the circumstances of the mishap, regardless of the results (Ergonomics). A proactive definition proposed by Harel and Weiss is:

A user command is a use error if the results do not comply with the designer’s intention.

An operational definition of use errors

The proactive definition is not operational, as intentions are not in the scope of common engineering practices. To enable detection of unexpected events, the definition is rephrased, using engineering terms, such as design requirements and guidelines. operative definition of a use error proposed by Harel and Weiss is:

A user command is a use error if it is not in the scope of predefined user commands appropriate to the operating scenario.

This definition complies with the STAMP model proposed by Nancy_Leveson. According to this model, normal use is defined by constrains to the system operation, and accidents may be attributed to deviation from these constrains.

This definition is operative, because:

• we know what are the predefined commands,
• we can formalize the operational scenarios, and,
• we can assign the user commands to operational procedures or constrains, associated with the operating scenario.

For example, the use error in the Torrey_Canyon accident may be described by:

• The predefined commands, including setting the steering control to either of the Manual, Automatic or Control position
• Formalizing the Navigation and the Maintenance operational scenarios
• Assigning the Control position to the Maintenance scenario, but not to the Navigation scenario.

External links

• IEC 62366:2007 - Medical devices -- Application of usability engineering to medical devices
• Department of Defense Human Factors Analysis and Classification System: A mishap investigation and data analysis tool
• Managing the Risks of Use Errors: The ITS Warning Systems Case Study
• The re-invention of human error
• Why "Human Error" is a Meaningless Concept
• Dekker: The Field Guide to Understanding Human Error
• Mitigating the Risks of Unexpected Events by Systems Engineering
• FDA Medical Devices Glossary
• Nancy Leveson home page