System Usability Scale

As I begin my research into User Experience (UX) methods, I’ve had to narrow down which methods I’ll be using. A super handy book for reviewing these is UX Methods: A Quick Guide to User Experience Research Methods. In one of my last blogs, Website Overhaul, I talk about Olallie Daylily Gardens, the lucky website that I’ll be researching. Their website is complex, crowded, and not very friendly. I’ve done my research and picked one of the two research methods I’ll be deploying, the System Usability Scale.

System Usability Scale

This method uses a fixed set of 10 statement to evaluate the usability of a system. Basically, the method is used when you want to quantify the perception of usability. My theory is that Olallie’s website is not user-friendly. The System Usability Scale won’t tell me what specific problems there are with the website, but it will give me knowledge on how much work the website needs.

How to Administer the SUS

I will ask volunteers to navigate the website at their leisure and then follow-up with some usability questions. The answers are on a scale from 1-5. 1 meaning the user strongly disagrees and 5 means strongly agree.

https://xd.adobe.com/ideas/process/user-testing/sus-system-usability-scale-ux/

Here’s the set of questions:

  1. I think I would like to use this website frequently.
  2. I found the website unnecessarily complex.
  3. I thought the website was easy to use.
  4. I think that I would need the support of a technical savvy person to use this website.
  5. I found the various functions in the website were well integrated.
  6. I thought there was too much inconsistency in the website.
  7. I would imagine that most people would learn to use this website very quickly.
  8. I found the website very cumbersome to use.
  9. I felt very confident in using the website.
  10. I needed to learn a lot of things before I could get going with this website.

How to Calculate the SUS Score

After I receive enough responses, I will calculate a SUS score. The results from each participant will be averaged and calculated. For each of the odd-numbered questions, I will subtract 1 from the score. For each of the even-numbered questions, I will subtract their value from 5. Then I will add up all the points and multiply by 2.5.

Example:

Odd = (4+5+3+4+3) = 19 – 5 = 14
Even = (2+1+3+1+1) = 25 – 8 = 17
SUS Score: (14+17) x 2.5 = 77.5

Odd – questions 1, 3, 5, 7, and 9
Even – questions 2, 4, 6, 8, and 10

What the Score Means

According to Usability Geek, here’s what the scores mean, out of 100 points.

  • 80.3 or higher is an A. People love your site and it’s easy to use.
  • 68 is the average. It’s around a C, could use improvement.
  • 51 or under is an F. Usability should be a priority and needs to be fixed.
https://xd.adobe.com/ideas/process/user-testing/sus-system-usability-scale-ux/

Case Study

A case study was performed to investigate the usability of a learning management system, Blackboard, with students from Jeddah Community College. An online survey was sent to 81 students and 25 responses were received. The findings indicate a SUS score of 64.5, just below the average. This means the system experiences usability issues.

https://www.researchgate.net/publication/311362711_THE_UTILIZATION_OF_SYSTEM_USABILITY_SCALE_IN_LEARNING_MANAGEMENT_SYSTEMS_A_CASE_STUDY_OF_JEDDAH_COMMUNITY_COLLEGE