Transcript .ppt

Software Usability
By: Robert J. Remington
EEL6883 – Software Engineering II
Dr. Turgut – University of Central Florida
Presented By: Adam Radwan
19 February 2007
Introduction
• 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 Quality
• Six ISO Standard high-level characteristics
to describe software quality
– Functionality
– Reliability
– Efficiency
– Maintainability
– Portability
– Usability
Usability
•
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?
Usability
• Five characteristics
– Understandability
– Learnability
– Operability
– Attractiveness (misspelled in the article)
– Compliance to application-related standards,
conventions, regulations in law, and protocols
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 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 usercentered development (UCD)
User-Centered Development
•
UCD process (ISO 13407) lists 4
activities undertaken during a project
1.
2.
3.
4.
Understand and specify the context of use
Specify the user and organizational requirements
Produce design solutions
Evaluate designs against requirements
Usability Design Standards
• ISO 9241 lists standards and guidelines for:
– Displayed colors
– Dialog principles
– Presentation of information
– User Guidance
– Menu Dialogs
– Form-filling Dialogs
Rapid 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 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 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
Summary
• 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?
• Any questions?
• Time permitting, brief navigation to several
websites displaying examples of usability