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"How to" series: System Usability Scale 2 (SUS2)

Updated: May 21

The System Usability Scale was originally developed by John Brooke in 1986, and provides a quick validated method for assessing the usability of a product. I have modified the original scale to make it easier to use. The simple scale is shown below, along with the scoring table.

I use SUS2 to compare iterations of a product or service I'm developing, or to compare products that are developed. An example of this was in helping a maternity service to choose their new CTG machines (machine used to assess the fetal wellbeing during late pregnancy/birth). We chose a few standardised tasks for a couple of midwives to complete on each CTG machine, then afterwards asked them to score their mental workload (using the NASA TLX - more on that later), and the SUS2. We had 2 clear winners that we were able to put forward into in person testing on the ward. We then used SUS2 again to gather feedback from a range of midwives and obstetricians on the ward when the 2 machines were in use, and the results of the SUS2 were able to guide us to the decision on the best CTG machine for the unit. (I'm happy to report the new machines are in use and the staff love them!).

In summary, the scale is quick, easy to use, and can help you add some quantitative data to your thoughts about usability of a device or a service.

This is the scale. Hand to the person who has been using the product/service [thing!], after they've completed a task, and get them to mark their scores. Add up all the scores and x2.5 to get the final score. Use the scoring guide below to see what result this gives you for usability.

The SUS2 scores from the survey can be used against this scoring table to give you adjectives to describe the usability, and also provide a guide to the acceptability range. These are validated from the earlier work completed by Brooke against trials of usability in a research setting.

When collating data from multiple users, I like to report the range of responses, as well as the average, as this can help in the interpretation of the data

Final note: In healthcare, healthcare staff often rate the usability of a product/service higher than you might expect - I think this is because there is so many devices with poor usability in our healthcare settings! So when using, keep this in mind, and consider having a baseline for your data (either with other products, or with a known product such as outlook for emails/teams etc.).

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