When I think of a product that's easy to use, I think of my Apple AirPods.
Right out of the case, they connect to my Apple devices via Bluetooth technology, so I can listen to music, take phone calls, and work on my laptop, all with great sound quality and no cords getting tangled.
I tell people how easy my AirPods are to use whenever they ask me about them, and after I did a little digging, I learned how important usability is to customer satisfaction. Think about it: If a product or service was hard to use, you probably wouldn't like paying for it very much.
Testing for usability is an important part of developing and improving a product. In this blog post, I'll dive into usability, and how it's measured using the System Usability Scale (SUS).
The Definition of Usability
The definition of "usability" is the quality of the user experience when using a product or a system, including websites, software, hardware, applications, or mobile devices. The goal of usability is to effectively and efficiently satisfy the end user.
There isn't one single aspect of usability when it comes to creating a usable product or system, but a combination of factors that can make it so, including:
Efficiency: How fast someone can use it
Intuitiveness: How effortlessly someone can understand it
Ease: How easy it is to use
Satisfaction: How much a user subjectively likes or dislikes using it
User-focused design helps product managers, designers, and engineers prioritize the user experience to help make the end-product as usable as possible. User testing over the course of product development can help make usability improvements that will benefit the end user, and the System Usability Scale (SUS) is a form of user testing you can employ.
What's the System Usability Scale (SUS)?
The System Usability Scale (SUS) is a 10-item Likert scale questionnaire that provides an at-a-glance look at the ease of use (or lack thereof) of websites, software, hardware, mobile devices, and other technological applications.
The SUS was created by John Brooke in 1986 to measure the usability of electronic office systems, but it's now applied to a wide variety of web or technology-based applications to measure how easy or difficult they are to use in order to improve.
System Usability Score Questions
The SUS consists of the following 10 questions that can be answered on a five-point Likert scale of "Strongly Disagree" to "Strongly Agree." In this example, we'll reference a website in the context of the questions, but these can be asked about products, websites, applications, hardware, or software.
1. I think that I would like to use this website frequently.
2. I found this website unnecessarily complex.
3. I thought this website was easy to use.
4. I think that I would need assistance to be able to use this website.
5. I found the various functions in this website were well integrated.
6. I thought there was too much inconsistency in this website.
7. I would imagine that most people would learn to use this website very quickly.
8. I found this website very cumbersome/awkward to use.
9. I felt very confident using this website.
10. I needed to learn a lot of things before I could get going with this website.
These questions ask, with a variety of different phrasing and nuance, questions about how easy or difficult it is to use whatever tool users are being surveyed about. Next, let's explore the benefits of using the SUS.
Benefits of Using the SUS Score
1. It provides an at-a-glance snapshot of how usable or unusable your system is.
By looking at a single number, anyone can understand how users feel about the usability of whatever you're evaluating.
2. It's easy to use, at scale or with a small number of respondents.
SUS surveys can be administered in-person, via email, or across a variety of other media to get the answers needed to evaluate the score.
How to Interpret SUS Score
1. Properly score your responses.
One fault of the SUS score is how complicated it is to interpret: You must add together the scores you receive, then multiply the sum by 2.5, to make the scores on a scale of 0-11. The score doesn't represent a percentage, but a sum of these new numbers.
2. Evaluate the score in context.
According to Usability.gov, a SUS score above a 68 is considered average, and anything below is considered below average. Alternately, you can group the number of scores you receive to determine what percentage of respondents gave you a high or low score.