Técnicas de Calidad en el Software Sesión # 10. Good quality software Operations Transition...

Técnicas de Calidad en el Software

Sesión # 10

Good quality software

Operations

TransitionTest

ing

• 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 walkthroughsStructured observationsHeuristic evaluationsGuidelines review

Acceptance tests (with real users)Think aloudExperimental studiesSurvey


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.


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.


Preparing a Cognitive Walkthrough

Example: Preparing a cognitive walkthrough for Testudo

Access: www.testudo.umd.edu

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.


Structured Observations


Evaluators analyze and document particular characteristics of a system.



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.


Preparing a Structured Observation

Example: Preparing a structured observation for Testudo

Access: www.testudo.umd.edu

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.


Heuristic Evaluation


Evaluators analyze particular characteristics of a system to determine conformance with pre-defined design principles.



Heuristic Evaluation

Example of pre-defined design principles:

1. Strive for consistency2. Cater to universal usability3. Offer informative feedback4. Design dialogues to yield closure5. Prevent errors6. Permit easy reversal of actions7. Support internal locus of control8. Reduce short-term memory load

(Shneiderman & Plaisant, 2005)


Guidelines Review


Evaluators analyze particular characteristics of a system to determine conformance with pre-defined design guidelines.



Guidelines review

Example of Web design guidelines for McKeldin Library staff.

Web authoring guidelinesWeb best practicesWeb color palette

http://www.lib.umd.edu/itd/web/bestpractices/colors.html


Guidelines review

Example of guidelines for the design and development of digital collections at UMD.

Text collectionsImage collectionsVideo collectionsAudio collections

(See PDF file)


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.


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.



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.


Experimental Studies

Involve:real usersobjective and measurable criteriaone or more system interfacesstatistical proceduresdiverse data sources:

log analysiseye-tracking analysis


Usability measures in experimental studies:Time to learnSpeed of performanceRate of errors by usersRetention over timeSubjective satisfaction

(Shneiderman & Plaisant, 2005)


Survey

It is a generally acceptable companion to expert reviews and experimental studies.

QUIS: standard survey instrument for usability assessment.


1. System experience

2. Past experience

3. Overall reactions to the system

4. Screen layout

5. Terminology

6. Learning

7. System capabilities8. Online help9. Online tutorials10. Media, I/O11. Teleconferencing12. Installation

QUIS: Questionnaire for User Interaction

Satisfaction (www.lap.umd.edu)


QUIS: Questionnaire for User Interaction

Satisfaction (www.lap.umd.edu)

• 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.

Técnicas de Calidad en el Software Sesión # 10. Good quality software Operations Transition...

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