What do you do when you have feedback that your product (oximeter, infusion pump, glucose monitor, etc.) is hard to use? It is not "user friendly". Perhaps there is a view in the press that a competitor's product is simpler. Maybe engineering is recommending a set of changes to improve usability.

How can you know that the investment necessary to make these changes will have the desired impact on usability? Often, there are conflicting opinions among the product development team on the changes needed to make your product more usable. You need a way to measure usability.

The best way to measure usability is by testing how well a product or prototype supports real clinical work. The usability test asks a sample of real users to perform (or simulate) real clinical tasks using your device while an observer measures their performance.

How well users perform tasks is measured by task success, time and accuracy. You know that product changes will have the desired impact on usability if they meet preset test objectives for these measures. An example of a test objective is: 8 of 10 representative users must be successful on the critical system tasks without assistance and in less time than with the primary competitor.

Care must be taken in setting the objectives. If possible, avoid armchair estimates such as "I think this task should take 20 minutes." Source your objectives by measuring the task success, time and accuracy of the current product version, or a competitor, or an alternative design.

Setting objectives generates additional value in that they help focus the product development team on what aspects of the product are critical for good usability. The team are all working toward the same goals. There is a consensus that "We need to do these things well."

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