시스템 사용성 척도(SUS)

The System Usability Scale (SUS) was developed by John Brooke in 1986 as a “quick and dirty” tool for usability practitioners. It consists of ten statements, five worded positively (e.g., “I thought the system was easy to use”) and five worded negatively (e.g., “I found the system unnecessarily complex”). This alternating tone helps prevent acquiescence bias. Users respond using a 5-point scale from “Strongly Disagree” to “Strongly Agree.” The scoring is slightly complex: for positive items, subtract 1 from the scale position; for negative items, subtract the scale position from 5. This results in all values ranging from 0 to 4. The sum of these values is then multiplied by 2.5 to obtain the final SUS score, which ranges from 0 to 100. It’s important to note that this is not a percentage; it’s a percentile score. A score of 68 is considered average. Despite its brevity, research has shown SUS to be reliable and valid across a wide range of interfaces, from hardware to software and websites. Its major advantages are that it is technology-agnostic, easy to administer, and provides a single score that is easy to communicate to stakeholders. It is often used after a usability test to capture the user’s overall impression of the system they just used.