Software UsabilitySoftware UsabilityBy: Robert J. RemingtonBy: Robert J. Remington

EEL6883 – Software Engineering IIEEL6883 – Software Engineering IIDr. Turgut – University of Central FloridaDr. Turgut – University of Central Florida

Presented By: Adam RadwanPresented By: Adam Radwan19 February 200719 February 2007

IntroductionIntroduction

• Initial thoughts– Frequently software engineers would like to

know if there are any good resources and documentation for designing a good GUI

– No magic bullet in design, rather there is a set of rules and suggestions outlined in SWEBOK

– IBM Report: 42% of users avoided ordering from the web when presented with a poorly designed user interface

Software QualitySoftware Quality

• Six ISO Standard high-level characteristics to describe software quality– Functionality– Reliability– Efficiency– Maintainability– Portability– Usability

UsabilityUsability

• Usability definition: “characteristics relating to the effort needed for use, and on the individual assessment of such use, by a stated or implied set of users”

• Discussion: What does this definition actually mean? Do the users have any implied prerequisites for system use?

UsabilityUsability

• Five characteristics– Understandability– Learnability– Operability– Attractiveness (misspelled in the article)

– Compliance to application-related standards, conventions, regulations in law, and protocols

Usability Engineering (UE)Usability Engineering (UE)

• Human-Computer Interaction (HCI) mismatches have caused fatal mistakes– Casey (Santa Barbara, CA ’93) reports a case

where a radiotherapy accelerator proton beam delivered a lethal 25 M eV as a result of a poorly designed, buggy user interface

• Usability Professionals Association (UPA) formed at ACM SIG-CHI ’92 by 30 delegates; now over 2000 members

UPA resourcesUPA resources

• Body of Knowledge spans studies done at 63 research and development centers

• Over 350 articles and laboratory reviews• Human-Computer Interaction journal

publishes many up-to-date articles• As a result, UE has expanded its process

models, design standards, and evaluation methodology all combines into user-centered development (UCD)

User-Centered DevelopmentUser-Centered Development

• UCD process (ISO 13407) lists 4 activities undertaken during a project

1. Understand and specify the context of use

2. Specify the user and organizational requirements

3. Produce design solutions

4. Evaluate designs against requirements

Usability Design StandardsUsability Design Standards

• ISO 9241 lists standards and guidelines for:– Displayed colors– Dialog principles– Presentation of information– User Guidance– Menu Dialogs– Form-filling Dialogs

Rapid PrototypingRapid Prototyping

• Creation of a limited, functional user interface for a “test drive” proven effective

• Allows for feedback to be obtained in earlier stages of development

• Helps avoid errors resulting in design problems from miscommunication about user requirements

Software Usability EvaluationSoftware Usability Evaluation

• Evaluation should take places at all stages of development

• Research centers often use laboratories with one-way mirrors, microphones, and cameras to monitor how a user may interact with a system for the first time

• Fitted curve can estimate the number of problems uncovered based on the number of evaluated users

• 5 users usually uncover approx. 80% of errors

Future ChallengesFuture Challenges

• Web-based user interfaces have been a limiting factor compared to traditional GUI development

• Smaller display size and limited input of mobile applications are current drawbacks with many portable implementations

• Some systems for I/O and control may best be kept on larger form-factor equipment

SummarySummary

• No single proven technique for development of high-usability software

• Usability Engineering becoming more advanced, contributions have increased overall software product quality

• Further HW/SW advances may solve some known limitations and drawbacks

Questions?Questions?

• Any questions?

• Time permitting, brief navigation to several websites displaying examples of usability