What does usability engineering mean?
In principle, usability engineering refers to the targeted analysis and development of the interfaces to the user. User interfaces are all points of interaction between the product and the user, or the patient. This includes obvious operating elements such as buttons, audio outputs, or the screen. Less apparent interfaces include, for example, the shape, the material of the housing, or graphic instructions on it. During development, it is extremely important to clearly identify these points and to develop them consciously and continuously. Changes in later development phases are often difficult, barely possible, or very costly.
How do you optimally implement usability in practice?
Usability engineering should already be incorporated during the definition of product requirements, that is, before the start of the development phase. That means requirements for the user interfaces must be treated on an equal footing with the other product requirements. This step ensures that usability is considered directly during user surveys that are conducted. As soon as an initial product concept is available, or the product owner or product manager has a rough picture of the product, the use specification should be created. This document serves as the starting point for the documentation and describes the product fundamentally from the perspective of usability.
The consideration and assessment of the product’s user interfaces should take place in parallel with development as part of the formative evaluation. The methods used for this can vary. For example, it makes sense to conduct initial smaller usability tests with a functional prototype that already has the relevant functions and interfaces implemented. The insights gained should then flow directly back into development and into improving the product.
Identifying risks early, even without a prototype
Even if there is not yet a physical product that can be tested, it is still possible to theoretically consider the defined functions and interfaces and identify potential weaknesses. A good method for this is, for example, the cognitive walkthrough, in which a moderator guides a user or expert through the tasks to assess whether they are understandable for the user.
Other options for evaluating usability include the following methods:
Brainstorm Use Scenarios
Several people independently brainstorm possible tasks and use scenarios.
Expert Review
Usability or product experts evaluate the user interfaces to identify possible risks.
Function Analysis
Assessment of which tasks can best be performed by the medical device or by the user, followed by assignment of the tasks.
Usability-Test
Simulation of the actual use of the product (in a real use environment with representative users).
Summative evaluation, demonstration of usability
At the end comes the summative evaluation. This provides the final assessment of whether the product is free of unacceptable use related risks (for example, treatment delay due to a plug that is very difficult to insert (USB vs. D SUB)). To do this, all functions must be fully implemented. This assessment is usually carried out through usability tests with actual users. The results of the summative evaluation must be compiled in a report that concludes the usability activities conducted alongside development.
But even after successful clearance and market entry, usability should not be neglected. Over the entire life cycle, feedback from the field can be used very easily to identify decisive potential improvements for the current product or for subsequent generations.
Usability as the foundation for sustainable success
A well thought out usability approach from the very beginning is a key success factor for modern medical devices. Those who define user interfaces early and consistently pursue their further development reduce rework and avoid expensive changes in later phases. Usability therefore not only provides the basis for a safe product, but also for a product that convinces its users and can thus be positioned successfully in the market over the long term.
