Usability

Definition

The extent to which specific people can achieve specified goals of effectiveness, efficiency, and satisfaction with a service or system (ISO 9241-210:2019).

Rationale

Usability is a fundamental outcome that should be considered at all stages of an HCD approach. Assessing usability early can help identify avoidable and costly issues that can be fixed and improve fit with users before larger-scale implementation of interventions and implementation strategies.  

Measuring & Understanding Usability

Researchers and designers use a variety of methods to understand a system or service’s usability, including: 

• Interviews, which ask about people’s experiences with a system or service
• Usability evaluations, in which experts review a system or service
  • Heuristic evaluations
  • Cognitive walkthroughs
• Usability testing, in which behavioral and subjective data about a system or study are gathered as people use a system or service in the field or in the lab.
• Surveys and standardized instruments (e.g., System Usability Scale). Learn about the Intervention, Implementation Strategy, and System Usability Scales (IUS/ISUS/SUS).

Within the context of DDBT (link to DDBT page), a formative usability evaluation aims to identify opportunities for design improvements and aligns with the Discover phase. A summative usability evaluation aims to evaluate how well a product or service meets its objectives and aligns with the Test phase.  

A goal of a usability evaluation is to answer usability questions and identify usability issues. Usability issues are aspects of the intervention or implementation strategy and/or a demand on the user which make it unpleasant, inefficient, onerous, or impossible for the user to achieve their goals in typical usage situations (adapted from Lavery, Cockton, & Atkinson, 1997).

Usability Questions 

A usability evaluation should be designed to answer specific questions you have about a system or service’s usability. These questions also guide selection of methods. Usability questions are similar to research questions and focus on what your usability test aims to understand about how users interact with a service or system. Example questions: 

Question	Type (Behavioral vs. Attitudinal)	Potential Methods
Do users think [this intervention or implementation strategy] is easy to use?	Attitudinal	Interview, focus group, surveys, or standardized instruments (e.g., SUS)
What would users want to change about [this intervention or implementation strategy]?	Attitudinal	Interview, focus group, survey
What obstacles could users encounter during [this intervention or implementation strategy]?	Attitudinal, Behavioral	Interview, focus group, heuristic evaluation, cognitive walkthrough, usability testing
What challenges do users experience when doing [this step of the intervention or implementation strategy]?	Behavioral	Usability testing, cognitive walkthrough

UWAC Reporting Requirements

To support center-wide science, UWAC-funded teams are required to report usability issues using the ALACRITY Center usability issue format, which includes: 

• A descriptive name
• A description of the issue
• Issue severity
• Issue scope
• Issue complexity
• Categorizing the issue (if possible) 

Usability issues should be reported at the end of the Discover phase, and then additionally identified issues should be reported at the end of discover/build and test phases. UWAC Methods Core members will provide feedback to teams after submission of usability issues to potentially revise wording and discuss how the usability issues will be addressed in subsequent DDBT stages.