Técnicas de Calidad en el Software Sesión # 10

Good quality software Operations Transition Testing Portability Reusability Interoperability Maintainability Flexibility Modularity Accuracy Confiability Integrity Usability (Pressman, 1993)

Good quality software Operations Transition Testing Portability Reusability Interoperability Maintainability Flexibility Modularity Accuracy Confiability Integrity Usability (Pressman, 1993)

Introduction to Usability Usability: the extent to which a system is easy to use by its target users. the quality of a user’s experience while interacting with a system. the elegance and clarity with which the interaction with a system is designed.

Introduction to Usability Usability evaluation: A systematic procedure to assess the extent to which a system is being accepted and valued by its target users. A means for measuring how well people can use a human-made object or system.

Usability Testing Strategies Expert reviews (without users) Cognitive walkthroughs Structured observations Heuristic evaluations Guidelines review Acceptance tests (with real users) Think aloud Experimental studies Survey

Usability Testing Strategies Cognitive Walkthroughs Involves expert evaluators and no users. Evaluators analyze and document the steps required for users to carry out key tasks, using a system. Evaluators report results and suggestions to design team and developers.

Usability Testing Strategies Preparing a Cognitive Walkthrough Hire an expert evaluator (usability specialist). Define user(s) profile(s). Provide access to a system prototype. Provide a list of key tasks supported by the system.

Usability Testing Strategies Preparing a Cognitive Walkthrough Example: Preparing a cognitive walkthrough for Testudo Access: Users: (a) Undergrad Students, (b) Grad Students, (c) Student Service Officers, (d) Bursar office employees. Key tasks: (a) login, (b) logout, (c) consult student account, (d) consult student schedule, (e) consult student transcript.

Usability Testing Strategies Structured Observations Involves expert evaluators and no users. Evaluators analyze and document particular characteristics of a system. Evaluators report results and suggestions to design team and developers.

Usability Testing Strategies Preparing a Structured Observation Hire an expert evaluator (usability specialist). Define user(s) profile(s). Provide access to a system prototype. A list of key system characteristics will be provided by the evaluator.

Usability Testing Strategies Preparing a Structured Observation Example: Preparing a structured observation for Testudo Access: Users: (a) Undergrad Students, (b) Grad Students, (c) Student Service Officers, (d) Bursar office employees. System characteristics: (a) Information Architecture, (b) Icon Design, (c) Consistency, (d) Security, (e) Interoperability, (d) Graphic Design, (e) Navigation Model.

Usability Testing Strategies Heuristic Evaluation Involves expert evaluators and no users. Evaluators analyze particular characteristics of a system to determine conformance with pre-defined design principles. Evaluators report results and suggestions to design team and developers.

Usability Testing Strategies Heuristic Evaluation Example of pre-defined design principles: 1.Strive for consistency 2.Cater to universal usability 3.Offer informative feedback 4.Design dialogues to yield closure 5.Prevent errors 6.Permit easy reversal of actions 7.Support internal locus of control 8.Reduce short-term memory load (Shneiderman & Plaisant, 2005)

Usability Testing Strategies Guidelines Review Involves expert evaluators and no users. Evaluators analyze particular characteristics of a system to determine conformance with pre-defined design guidelines. Evaluators report results and suggestions to design team and developers.

Usability Testing Strategies Guidelines review Example of Web design guidelines for McKeldin Library staff. Web authoring guidelines Web best practices Web color palette actices/colors.html

Usability Testing Strategies Guidelines review Example of guidelines for the design and development of digital collections at UMD. Text collections Image collections Video collections Audio collections (See PDF file)

Usability Testing Strategies Integrating results from expert reviews Organize regular meetings with the evaluator. Identify those design suggestions which are relevant and feasible. Include design suggestions in the system prototype. Test the new prototype version with real users.

Usability Testing Strategies Think Aloud Involves real users. Users are asked to carry out key tasks, using a system. A usability specialist observes and documents users’ reactions to the system. Evaluators report results and suggestions to design team and developers.

Usability Testing Strategies Preparing a Think Aloud session Design a list of key tasks to be carried out by users. Invite as many representative users as possible. Explain users that the session is about assessing the system usability, not his/her performance. Hire a usability specialist to run the sessions, and to observe and document the users’ reactions to the system. Usability specialists will report results and suggestions to design team and developers.

Usability Testing Strategies Experimental Studies Involve: real users objective and measurable criteria one or more system interfaces statistical procedures diverse data sources: log analysis eye-tracking analysis

Usability Testing Strategies Usability measures in experimental studies: Time to learn Speed of performance Rate of errors by users Retention over time Subjective satisfaction (Shneiderman & Plaisant, 2005)

Usability Testing Strategies Survey It is a generally acceptable companion to expert reviews and experimental studies. QUIS: standard survey instrument for usability assessment.

Usability Testing Strategies 1. System experience 2. Past experience 3. Overall reactions to the system 4. Screen layout 5. Terminology 6. Learning 7. System capabilities 8. Online help 9. Online tutorials 10. Media, I/O 11. Teleconferencing 12. Installation QUIS: Questionnaire for User Interaction Satisfaction (

Usability Testing Strategies QUIS: Questionnaire for User Interaction Satisfaction ( Pre-defined sections Pre-defined answers Self-perceived user satisfaction Issues: Digital or print format? Response rate

Usability Testing Plan A usability testing plan: Includes diverse strategies, with users and expert reviews. Should be part of a system design and development project. Depends on the nature of the system being developed, and the target users.