System Usability Scale

A quick and effective method for determining the usability of a website or application using a standardized questionnaire.

About

The System Usability Scale (SUS) is a widely used questionnaire that measures the perceived usability of a product or system. Comprising ten standardized questions, the SUS provides a reliable and quick assessment of user satisfaction and ease of use. It's valuable in usability testing, user experience evaluation, and product development, where understanding how users perceive usability guides design refinement, quality assurance, and user-centric optimization.

Suitable for

  • Quantitative usability testing of the system
  • Remote testing
  • Assessing system usability

Deliverables

System Usability Scale Survey

A standardized 10-item questionnaire to measure the perceived usability of the system across different user groups and platforms.


Participant Demographics

A summary of the background information of the participants, including age, gender, and other relevant attributes, to help identify any user-specific differences in responses.


Data Collection Plan

A detailed outline of when and how the System Usability Scale surveys will be administered to the target users.


Quantitative Results

A report consisting of the aggregated and averaged raw System Usability Scale scores, including individual item scores, for each user group and platform.


Usability Benchmark

A comparison of the System Usability Scale scores to established industry or application-specific benchmarks to determine the relative usability of the system.


Insights & Recommendations

An analysis of the quantitative results, including identification of potential usability issues and areas for improvement, along with actionable recommendations for system enhancements.


Data Visualization

Graphical representations of the combined System Usability Scale scores to help communicate the usability strengths and weaknesses of the system to stakeholders.


Longitudinal Analysis

A tracking of System Usability Scale scores over time to assess the impact of system enhancements and better understand trends in user satisfaction.

Procedure

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Step 1: Understanding System Usability Scale (SUS)

SUS is a simple, 10-item questionnaire that provides a global view of the perceived usability of a product or system. Each question contributes to a total score out of 100, which can be used to measure overall usability.

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Step 2: Preparing the SUS questionnaire

Create a questionnaire with the 10 standard SUS questions. 5 questions are positively worded, while the remaining 5 are negatively worded. Each question should be answerable using a 5-point Likert scale, ranging from Strongly Disagree (1) to Strongly Agree (5).

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Step 3: Participant recruitment

Identify and recruit a representative sample of users who will test the product or system. The number of participants may vary depending on the project size, but it's recommended to have at least 5-8 participants.

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Step 4: Conducting usability testing

Ask participants to complete a series of tasks using the product or system. Record their interactions and observe how they interact with the interface to identify usability issues or areas for improvement.

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Step 5: Administering the SUS questionnaire

After completing usability testing, ask participants to fill out the SUS questionnaire to obtain their feedback on the perceived usability of the product or system.

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Step 6: Scoring the SUS questionnaire

To calculate the SUS score, first subtract 1 from the response values of odd-numbered items (positively worded) and subtract the response values of even-numbered items from 5 (negatively worded). Then sum up the new values and multiply by 2.5. The resulting value is the total SUS score out of 100.

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Step 7: Analyzing the results

Examine the total SUS scores, as well as individual response patterns, to identify areas of high and low perceived usability. A higher SUS score indicates better usability, with a score above 68 considered above average.

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Step 8: Reporting and recommendations

Compile the findings from the usability testing and the SUS questionnaire in a comprehensive report. Use these findings to make recommendations for improving the product or system's usability.

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Step 9: Iterating and retesting

Make the recommended improvements to the product or system and conduct additional rounds of usability testing and SUS questionnaires to measure the impact of these changes on the perceived usability.

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