User-Centered Design (UCD)
CS 352 Usability Engineering
Summer 2010
Announcements
• Quiz tomorrow (Ch 1, 2’s readings, up to
today’s lectures)
• Readings:
– Finish reading Ch 2.
– ('07 version)Read 9.2. ('02 version) Read 9.2 and
9.3. Just skim b’c we will cover them in detail in
today’s lecture.
• Project proposal part 1, 2 due next Tue, part 3
due next Thu.
2
Review of this week’s lectures on
design
• The PRICPE process
Pre-dispositions
Research
Insights
Concept
Prototype
Evaluation
Where does the user come in?
Today and next few days’ lectures
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User-Centered Design Principles [ch. 9]
• Early and continual focus on users and tasks
• Empirical measurement
• Iterative design
4
User-Centered Design Principles [ch. 9]
 Early and continual focus on users and tasks
• Empirical measurement
• Iterative design
5
Early focus on users and tasks
1.
Users’ tasks and goals are the driving force behind the
development.
“Where can we deploy this new technology?” vs. “What technologies are
available to provide support for users’ goals?”
2.
Users’ behavior and context of use are studied and the system is
designed to support them.
– Highlights preferences, priorities, implicit intentions
– E.g., (Fahmy & Spencer) Families keep shopping lists  a reusable
virtual shopping list
– E.g., (Jeen, Moon & Rob) People are on-the-go  Google Map
– E.g., (Greg & Scott) Touch screen in the kitchen  large buttons
3.
Users’ characteristics are captured and designed for.
– E.g., (Brian & Chris) Seniors are risk-aware and don’t want to send
their credit card numbers over the internet  pay upon arrival
6
Early focus on users and tasks
(cont.)
4. Users are consulted
throughout development
from earliest phases to the
latest, and their input is
seriously taken into account.
5. All design decisions are taken
within the context of the
users, their work, and their
environment.
Keep your
users in
mind at
all times!!
7
User-Centered Design Principles [ch. 9]
• Early and continual focus on users and tasks
 Empirical measurement
• Iterative design
8
Empirical measurement
• Empirical - derived from experiment and
observation (wordnetweb.princeton.edu)
• Empirical measurement for usability and user
experience goals
– Allows designers to evaluate their designs
– Help designers choose between alternatives
9
User-Centered Design Principles [ch. 9]
• Early and continual focus on users and tasks
• Empirical measurement
 Iterative design
10
Iterative design
11
Some practical issues
•
•
•
•
Who are the users?
What do we mean by needs?
How do you generate alternative designs?
How do you choose among alternatives?
12
Some practical issues
 Who are the users?
• What do we mean by needs?
• How do you generate alternative designs?
• How do you choose among alternatives?
13
Who are the users?
• People who
– directly use the system to achieve a task
– manage the direct users
– make the purchasing decision
• Primary (frequent hands-on users)
Secondary (occasional users)
Tertiary (those affected by the intro of system or who will
influence its purchase)
• Stakeholders – “people or organizations who will be
affected by the system and who have a direct or indirect
influence ” [Kotonya & Sommerville ‘98]
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Activity
• Who do you think are the stakeholders for the
check-out system of a large supermarket?
• Possible answers:
– Check-out operators
– Customers (right amount, correct receipt, quick &
efficient)
– Supermarket managers, supermarket owners (want
assistants happy, customers satisfied, don’t want to
lose money)
– Others, e.g., warehouse staff, suppliers, …
15
Some practical issues
• Who are the users?
 What do we mean by needs?
• How do you generate alternative designs?
• How do you choose among alternatives?
16
What do we mean by “needs”?
Designer: “What do you need?”
User:“I need blah, blah, blah…”
Designer:“Ok, let’s do that!”
Is this always the case?
No, often times, user do NOT know what they
want!!!
17
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
– What they are trying to achieve
– How they achieve it currently
– Whether they would achieve their goals more
effectively
18
Users do not always know what they
need…
• We approach this by understanding …
 The characteristics and capabilities of the user
– What they are trying to achieve
– How they achieve it currently
– Whether they would achieve their goals more
effectively
19
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
Physical
• e.g., size of hands
decides size of keys of a
keyboard
• e.g., motor disabilities
 eye tracking input
20
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
Cognitive
 memory, e.g., the
magical number of 7+2
• perception
• problem-solving
• learning
• attention
• …
21
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
Law of Proximity
Cognitive
• memory, e.g., the magical
number of 7+2
 perception
• problem-solving
• learning
• attention
• …
Pictures on visual perceptions from http://www.interactiondesign.org/encyclopedia/gestalt_principles_of_form_perception.html
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Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
– What they are trying to achieve
Case Study:
– How they achieve it currently
StratCell
– Whether they would achieve their goals more
effectively
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StratCell [Grigoreanu et al. ‘10]
• A spreadsheet
system with
debugging aid
• Target users:
spreadsheet users
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So what do we do?
• We approach it by understanding …
– The characteristics and capabilities of the user
 What they are trying to achieve
Case Study:
– How they achieve it currently
StratCell
– Whether they would achieve their goals more
effectively
25
What users are trying to achieve?
• Reliable spreadsheets
“Barclays Capital agreed to purchase some of Lehman’s assets
but, due to a spreadsheet error resulting from hidden
dependencies, the company purchased assets for millions of
dollars more than they had intended [13].” [Grigoreanu et al. ‘10]
• Task:
– finding and fixing errors in spreadsheets
26
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
– What they are trying to achieve
Case Study:
 How they achieve it currently
StratCell
– Whether they would achieve their goals more
effectively
27
How users currently achieve it?
• User studies!!!
PResearchICPE
UCD’s “early &
– Lab study, task to debug spreadsheets
continual focus
– Interaction logs, self-reported questionnaire
on the user”
principle
• Findings: PR Insights CPE
– 8 debugging strategies including Testing, Code
Inspection, Dataflow, To-do Listing, etc.
28
Users do not always know what they
need…
• We approach this by understanding …
– The characteristics and capabilities of the user
– What they are trying to achieve
– How they achieve it currently
 Whether they would achieve their goals more
effectively
29
Help users achieve their goals more
effectively
PR Insights
Concept Prototype
E
UCD’s “iterate”
principle
PRICP
Evaluate
UCD’s “empirical
measurement”
principle
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Take-away
• Users did not say “I need a tool to help me
debug my spreadsheets”.
• It is the designer’s job to help the users figure
out what they really need!
31
Some practical issues
• Who are the users?
• What do we mean by needs?
 How do you generate alternative designs?
• How do you choose among alternatives?
32
How do you generate alternative
designs?
• One pragmatic answer:
– “…alternatives come from looking at other similar
designs, and the process of inspiration and
creativity can be enhanced by prompting a
designer’s own experience and by looking at
others’ ideas and solutions.” [text p435 ‘07 ver.]
• One caveat:
– May become overly influenced by others’ ideas
33
Activity
Consider yesterday’s online grocery system you
designed.
1. Reflecting on the process again, what do you
think inspired your outline design?
2. See if you can identify any elements within it
that you believe are truly innovative.
34
Some practical issues
• Who are the users?
• What do we mean by needs?
• How do you generate alternative designs?
 How do you choose among alternatives?
35
How do you choose among
alternatives?
• Possible answers:
– External (users can see) vs. internal (users cannot
see) features
• In usability engineering, the driving force behind the
design is the way the users interact with the product 
External!
• This is not to say internal features are unimportant.
– Let users and stakeholders interact w/ your
designs  requires prototyping (more coming
later in this course)
36
Announcement
• Quiz tomorrow
• Reading: ('07 version)Read 9.2. ('02 version)
Read 9.2 and 9.3. Just skim because we have
already covered them in detail in today’s
lecture.
• Project proposal due next Tue.
37
Announcements
• Quiz tomorrow (Ch 1, 2’s readings, up to
today’s lectures)
• Readings:
– Finish reading Ch 2.
– ('07 version)Read 9.2. ('02 version) Read 9.2 and
9.3. Just skim b’c we will cover them in detail in
today’s lecture.
• Project proposal part 1, 2 due next Tue, part 3
due next Thu.
38