The Standardized Usability Scale, commonly referred to as SUS, has become a widely accepted and widely used tool in the field of usability engineering. It’s a simple, 10-item questionnaire that measures the usability of a product or system, providing a quick and reliable way to assess the user experience. But have you ever wondered when SUS was invented? In this article, we’ll delve into the history of SUS, exploring its origins, evolution, and impact on the field of usability.
A Brief History of Usability Engineering
Before we dive into the history of SUS, it’s essential to understand the context in which it was developed. Usability engineering, as a field, has its roots in the 1980s, when the first personal computers were introduced to the market. As technology became more accessible and user-friendly, the need for usability testing and evaluation grew. In the early days, usability testing was primarily focused on identifying usability problems, rather than measuring the overall usability of a product.
The Need for a Standardized Usability Scale
In the late 1980s, the US Department of Defense (DoD) recognized the need for a standardized usability scale that could be used across different products and systems. The DoD was looking for a way to evaluate the usability of its systems, which were becoming increasingly complex and user-unfriendly. In response to this need, a team of researchers at the DoD’s Human Engineering Laboratory, led by John Brooke, began working on a new usability scale.
The Birth of SUS
In 1986, John Brooke published a paper titled “SUS: A ‘Quick and Dirty’ Usability Scale,” in which he introduced the Standardized Usability Scale. The original SUS questionnaire consisted of 10 items, each with a 5-point Likert scale, ranging from “Strongly Disagree” to “Strongly Agree.” The items were designed to assess the usability of a product or system, covering aspects such as ease of use, complexity, and user satisfaction.
The SUS Questionnaire
The SUS questionnaire is simple and easy to administer. It consists of the following 10 items:
- I think that I would like to use this system frequently.
- I found the system unnecessarily complex.
- I thought the system was easy to use.
- I think that I would need the support of a technical person to be able to use this system.
- I found the various functions in this system were well integrated.
- I thought there was too much inconsistency in this system.
- I would imagine that most people would learn to use this system very quickly.
- I found the system very cumbersome to use.
- I felt very confident using the system.
- I needed to learn a lot of things before I could get going with this system.
Evaluation and Scoring
The SUS questionnaire is scored on a scale of 0 to 100, with higher scores indicating better usability. The scoring is based on the sum of the scores for each item, with some items being reversed to ensure that the scale is consistent. The SUS score is then calculated using a formula that takes into account the number of items and the response scale.
Interpretation of SUS Scores
SUS scores can be interpreted in various ways, depending on the context and purpose of the evaluation. Here are some general guidelines for interpreting SUS scores:
- Scores above 80 indicate excellent usability.
- Scores between 70 and 79 indicate good usability.
- Scores between 60 and 69 indicate fair usability.
- Scores below 60 indicate poor usability.
Impact of SUS on Usability Engineering
The introduction of SUS had a significant impact on the field of usability engineering. It provided a standardized tool for evaluating usability, which enabled researchers and practitioners to compare the usability of different products and systems. SUS also helped to establish usability as a key aspect of product design, highlighting the importance of user-centered design.
Advantages of SUS
SUS has several advantages that have contributed to its widespread adoption:
- Ease of use: SUS is simple to administer and score, making it a quick and efficient way to evaluate usability.
- Standardization: SUS provides a standardized tool for evaluating usability, enabling comparisons across different products and systems.
- Reliability: SUS has been shown to be a reliable measure of usability, with high levels of internal consistency and test-retest reliability.
Criticisms and Limitations of SUS
While SUS has been widely adopted and has had a significant impact on the field of usability engineering, it has also been subject to criticism and limitations. Some of the limitations of SUS include:
- Limited scope: SUS only evaluates usability and does not take into account other aspects of user experience, such as user satisfaction and engagement.
- Lack of context: SUS does not provide context-specific information about usability, making it difficult to identify specific usability problems.
Alternatives to SUS
In recent years, alternative usability scales have been developed, which address some of the limitations of SUS. Some of these alternatives include:
* **System Usability Scale (SUS)**: A modified version of SUS that includes additional items to assess user satisfaction and engagement.
* **User Experience Questionnaire (UEQ)**: A questionnaire that assesses user experience across multiple dimensions, including usability, user satisfaction, and engagement.
Conclusion
In conclusion, the Standardized Usability Scale (SUS) has had a significant impact on the field of usability engineering. Developed in 1986 by John Brooke, SUS has become a widely accepted and widely used tool for evaluating usability. While it has its limitations, SUS remains a valuable tool for researchers and practitioners, providing a quick and reliable way to assess the usability of products and systems. As technology continues to evolve, it’s likely that SUS will continue to play an important role in shaping the user experience.
What is the Standardized Usability Scale (SUS)?
The Standardized Usability Scale (SUS) is a widely used questionnaire in the field of human-computer interaction and usability engineering. It is a simple, 10-item questionnaire that is used to assess the usability of a product or system. The SUS questionnaire asks users to rate their level of agreement with a series of statements related to the usability of the product or system.
The SUS questionnaire is widely used because it is easy to administer and provides a quick and reliable way to assess the usability of a product or system. The results of the SUS questionnaire can be used to identify areas for improvement and to compare the usability of different products or systems.
Who developed the Standardized Usability Scale (SUS)?
The Standardized Usability Scale (SUS) was developed by John Brooke in 1986. Brooke was a British engineer who worked at Digital Equipment Corporation (DEC) at the time. He developed the SUS questionnaire as a way to assess the usability of DEC’s products and systems.
Brooke’s work on the SUS questionnaire was groundbreaking because it provided a standardized way to assess usability. Prior to the development of the SUS questionnaire, usability assessments were often subjective and varied widely from one study to another. The SUS questionnaire provided a reliable and consistent way to assess usability, which has made it a widely used tool in the field of human-computer interaction.
What is the purpose of the Standardized Usability Scale (SUS)?
The primary purpose of the Standardized Usability Scale (SUS) is to assess the usability of a product or system. The SUS questionnaire is designed to provide a quick and reliable way to assess the usability of a product or system, and to identify areas for improvement. The results of the SUS questionnaire can be used to compare the usability of different products or systems, and to track changes in usability over time.
The SUS questionnaire is also used to evaluate the effectiveness of usability improvements. By administering the SUS questionnaire before and after making changes to a product or system, designers and developers can assess the impact of those changes on usability. This information can be used to inform design decisions and to ensure that products and systems are designed with the user in mind.
How is the Standardized Usability Scale (SUS) administered?
The Standardized Usability Scale (SUS) questionnaire is typically administered to users after they have interacted with a product or system. The questionnaire asks users to rate their level of agreement with a series of statements related to the usability of the product or system. The questionnaire is usually administered online or in-person, and takes only a few minutes to complete.
The SUS questionnaire can be administered in a variety of settings, including in-person usability testing, online surveys, and field studies. The questionnaire can be administered to a small group of users or to a large sample of users, depending on the goals of the study. The results of the SUS questionnaire can be analyzed using a variety of statistical methods, including descriptive statistics and inferential statistics.
What are the benefits of using the Standardized Usability Scale (SUS)?
The Standardized Usability Scale (SUS) has a number of benefits, including its ease of use, reliability, and validity. The SUS questionnaire is easy to administer and takes only a few minutes to complete, making it a quick and efficient way to assess usability. The questionnaire is also reliable, meaning that it produces consistent results across different studies and populations.
The SUS questionnaire is also a valid measure of usability, meaning that it accurately assesses the usability of a product or system. The questionnaire has been widely used in a variety of studies and has been shown to be a reliable and valid measure of usability. The results of the SUS questionnaire can be used to inform design decisions and to ensure that products and systems are designed with the user in mind.
What are the limitations of the Standardized Usability Scale (SUS)?
The Standardized Usability Scale (SUS) has a number of limitations, including its lack of sensitivity to certain types of usability issues. The SUS questionnaire is a general measure of usability, and may not be sensitive to specific usability issues, such as accessibility or user experience. The questionnaire is also limited in its ability to provide detailed, qualitative feedback about usability issues.
The SUS questionnaire is also limited in its ability to assess the usability of complex systems or products. The questionnaire is designed to assess the usability of a single product or system, and may not be suitable for assessing the usability of complex systems or products that have multiple components or interfaces. The results of the SUS questionnaire should be interpreted in conjunction with other usability metrics and methods.
How has the Standardized Usability Scale (SUS) been used in practice?
The Standardized Usability Scale (SUS) has been widely used in practice to assess the usability of a variety of products and systems, including software applications, websites, and medical devices. The questionnaire has been used in a variety of settings, including in-person usability testing, online surveys, and field studies.
The SUS questionnaire has been used by a variety of organizations, including technology companies, healthcare organizations, and government agencies. The questionnaire has been used to inform design decisions, to evaluate the effectiveness of usability improvements, and to compare the usability of different products or systems. The results of the SUS questionnaire have been used to improve the usability of a wide range of products and systems, and to ensure that products and systems are designed with the user in mind.