What about Chapter 7?
Let’s focus on usability–A
usability initiative needs
usability goal(s). In Web
C, what were the
Evaluation Objectives?
Our author defines
usability requirements as:
The desired qualitative or
quantitative usability
goals for a system
What is the usability
process?
Time to complete task.
Percentage of task
completed
3.
Percentage of task
completed per unit time
(speed metric.
4.
Ratio of successes to
failures.
5.
Time spent on errors.
6.
Percentage or number of
errors.
7.
Percentage or number of
competitors that do this
better than current product.
8.
Etc.
What are these?
1.
2.
Tyldesley’s 22 possible
Measurement Criteria
UIDE Chapter 6




Learnability – time and effort required to
reach a specified level of use performance
Throughput – tasks accomplished by
experienced users, speed, and errors
Flexibility – extent to which system can
accommodate changes
Attitude – positive attitude of users
UIDE Chapter 6
The Modern-Day View of Usability
◦ 5 E’s





Effective
Efficient
Engaging
Error tolerant
Easy to learn
Constraints and Trade-offs in Relation to
Requirements Gathering
◦ Costs/Budgets/Timescales
◦ Technical Constraints
◦ Trade-Offs
What is the cost of a defect in requirements?
UIDE Chapter 6

Requirements
Specification
◦ User
characteristics
◦ Tasks and task
characteristics
◦ Environmental
factors
◦ Usability
◦ Constraints and
trade-offs
UIDE Chapter 6
◦ Purposes of Prototyping: Why Bother Trying Out
Your Ideas?
 Check feasibility of ideas with users
 Check usefulness of the application
 Allow users to contribute
 Allow users to test ideas
 Validate requirements
 Negotiate requirements
UIDE Chapter 6
◦ Low-Fidelity Prototypes
 Sketching
 Screen Mockups
 Storyboards
UIDE Chapter 6


High-Fidelity
Prototypes: Using
Software Tools to
Try Out Your Ideas
Cautions about
Prototyping
UIDE Chapter 6


Creating the physical
Design of the user
interface (UI)
Issue of work
reengineering
User needs
and
requirements
◦ Power
◦ Efficiency
◦ Effective support of
business goals
UIDE Chapter 8

Book Example in Ch. 8.1
◦ Introduction to the Digital Library
◦ Work Reengineering for the Digital Library
◦ Task Allocation for the Digital Library

Graphical User Interface (GUI) Project
◦ Introduction to your idea about organization of
your “computing devices”
◦ Web E the pitching of ideas for a new
interactive graphical user interface.
UIDE Chapter 8

Part 1 – Usability
◦ Usability Attributes for system development
◦ User Interface Matters
◦ Costs related to poor UI

Part 2 – Requirements

Part 3 – Design
◦ How to gather requirements and create user stories
◦ True Users – Persona – User’s Domains
◦ Describing Users’ Work
◦ Conceptual Design
◦ Choosing for the user’s best devices, interaction, etc.
UIDE Chapter 8

A University department has
◦ Users: _________ __________ _________________
◦ Tasks: ____________________________
◦ Individuals have personal libraries to share

Business Motivation for New Digital Library
◦ _______________________
◦ Track personal resources.
UIDE Chapter 8


Work differently if to work effectively
Goals:
◦ Power and efficiency that automation makes possible
◦ More effectively support business goals
◦ Minimize retraining

To Begin DO:

Task Scenario: represents the present situation.

Use Scenario: description of the anticipated use
of the new UI.
UIDE Chapter 8
Create a
user’s task
with
setting for
an
evaluation
from
these.
UIDE Chapter 8
UIDE Chapter 8


Sharing the different “essential” tasks
between the user and the computer.
Essential use case:
◦ Index card with User’s Purpose
Responsibility
- System
Fig 8.3
UIDE Chapter 8

The process of establishing the underlying
organization and structure of a UI
Content diagram – low fidelity prototype that
represents the organization and structure of the
user interface from the designer’s perspective.
Fig 8.5
UIDE Chapter 8

Design needs:
◦ Derived concrete use cases
◦ Identify primary task objects, attributes, actions
◦ Identify the containers and the task objects in each
one
◦ Link containers to s
◦ how navigation flow.
UIDE Chapter 8

Deriving from Essential Use case.
Fig 8.6
UIDE Chapter 8
 Conceptual
Design
◦ Deriving Concrete Use Cases from Essential Use
Cases
◦ Identifying Task Objects, Attributes, and Actions
 Task Objects
 Attributes
 Actions
UIDE Chapter 8

Task Objects: units of information or data with
which the users interact to carry out their tasks.
◦ Includes Class objects, i.e. media types, members of the
library

Task Attributes: task object components
◦ Properties and Child Objects
 Title and author are properties of book
 Owner of CD-ROM is child object of CD-ROM because Owner
has its own properties

Task Actions: actions performed on task objects
◦ Allocating guests to rooms. (Add)
◦ Create, delete, copy , save, edit, etc.
UIDE Chapter 8


Task objects – single underline
Attributes of objects – double underline
Fig 8.8
UIDE Chapter 8
Fig 8.9

Prototyping Task Objects, Attributes, and
Actions
UIDE Chapter 8
Use of “Sticky
Notes to
prototype task
objects,
attributes, and
actions.
Fig 8.10
UIDE Chapter 8
Template for Containers
Fig 8.11
UIDE Chapter 8
Fig 8.12
Double Link
UIDE Chapter 8

Main Container
Fig 8.13
UIDE Chapter 8
Fig 8.14
UIDE Chapter 8
 Template for
Containers
 The Main Container
 Other Containers
 Links
 Prototyping Containers
and Links
 Final Thoughts on
Conceptual Design
UIDE Chapter 8
UIDE Chapter 8