Discount Evaluation
Evaluating with experts
Agenda
Online collaboration tools Heuristic Evaluation Perform HE on each other’s prototypes Cognitive Walkthrough Perform CW on each other’s prototypes
Project part 3
See any comments in your writeups I’ll send out grades tomorrow (I have to add the
demo piece) Perform the evaluations
Clearly inform your users what you are doing and why.
If you are audio or video recording, I prefer you use a consent form.
Pilot at least once – know how long its going to take.
If you need equipment, ask me
Discount Evaluation Techniques
Basis: Observing users can be time-consuming and
expensive Try to predict usability rather than observing it
directly Conserve resources (quick & low cost)
Approach - inspections
Expert reviewers used HCI experts interact with system and try to find
potential problems and give prescriptive feedback
Best if Haven’t used earlier prototype Familiar with domain or task Understand user perspectives
Does not require working system
Heuristic Evaluation
Developed by Jakob Nielsen
Several expert usability evaluators assess system based on simple and general heuristics (principles or rules of thumb)
(Web site: www.useit.com)
How many experts?
Nielsen found thatabout 5 evaluations found 75% of the problems
Above that you get more, but at decreasing efficiency
Evaluate System
Reviewers need a prototype May vary from mock-ups and storyboards to a
working system
Reviewers evaluate system based on high-level heuristics.
Where to get heuristics? http://www.useit.com/papers/heuristic/ http://www.asktog.com/basics/firstPrinciples.html
Heuristics
use simple and natural dialog
speak user’s language
minimize memory load
be consistent provide feedback
provide clearly marked exits
provide shortcuts provide good error
messages prevent errors
Neilsen’s Heuristics
visibility of system status
aesthetic and minimalist
design user control and
freedom consistency and
standards error prevention
recognition rather than recall
flexibility and efficiency of use
recognition, diagnosis and recovery from errors
help and documentation match between system
and real world
Groupware heuristics Provide the means for intentional and appropriate verbal
communication Provide the means for intentional and appropriate gestural
communication Provide consequential communication of an individual’s embodiment Provide consequential communication of shared artifacts (i.e. artifact
feedthrough) Provide Protection Manage the transitions between tightly and loosely-coupled
collaboration Support people with the coordination of their actions Facilitate finding collaborators and establishing contact
Baker, Greenberg, and Gutwin, CSCW 2002
Ambient heuristics
Useful and relevant information “Peripherality” of display Match between design of ambient display and
environments Sufficient information design Consistent and intuitive mapping Easy transition to more in-depth information Visibility of state Aesthetic and Pleasing Design
Mankoff, et al, CHI 2003
Process
Perform two or more passes through system inspecting Flow from screen to screen Each screen
Evaluate against heuristics Find “problems”
Subjective (if you think it is, it is) Don’t dwell on whether it is or isn’t
Debriefing
Organize all problems found by different reviewers At this point, decide what are and aren’t
problems Group, structure Document and record them
Severity Rating
Based on frequency impact persistence market impact
Rating scale 0: not a problem 1: cosmetic issue, only fixed if extra time 2: minor usability problem, low priority 3: major usability problem, high priority 4: usability catastrophe, must be fixed
Advantages
Few ethical issues to consider Inexpensive, quick
Getting someone practiced in method and knowledgeable of domain is valuable
Challenges
Very subjective assessment of problems Depends of expertise of reviewers
Why are these the right heuristics? Others have been suggested
How to determine what is a true usability problem Some recent papers suggest that many
identified “problems” really aren’t
Your turn:
Library – main page, finding a book
Use Nielsen’s heuristics (p 686) List all problems Come up to the board and put up at least one
new one We’ll rate as a group
Your turn
Prepare Determine your heuristics if you want any different
ones Demo your prototype to all of us
Evaluate Evaluate someone other than yourself
Debrief On your own, include in Part 3
Cognitive Walkthrough
More evaluation without users
Cognitive Walkthrough
Assess learnability and usability through simulation of way novice users explore and become familiar with interactive system
A usability “thought experiment” Like code walkthrough (s/w engineering) From Polson, Lewis, et al at UC Boulder
CW: Process
Construct carefully designed tasks from system spec or screen mock-up
Walk through (cognitive & operational) activities required to go from one screen to another
Review actions needed for task, attempt to predict how users would behave and what problems they’ll encounter
CW: Assumptions
User has rough plan User explores system, looking for actions to
contribute to performance of action User selects action seems best for desired
goal User interprets response and assesses
whether progress has been made toward completing task
CW: Requirements
Description of users and their backgrounds Description of task user is to perform Complete list of the actions required to
complete task Prototype or description of system
CW: Methodology
Step through action sequence Action 1 Response A, B, .. Action 2 Response A ...
For each one, ask four questions and try to construct a believability story
CW: Questions
1. Will users be trying to produce whatever effect action has?
2. Will users be able to notice that the correct action is available? (is it visible)
3. Once found, will they know it’s the right one for desired effect? (is it correct)
4. Will users understand feedback after action?
CW: Answering the Questions
1. Will user be trying to produce effect? Typical supporting evidence
It is part of their original task They have experience using the system The system tells them to do it
No evidence? Construct a failure scenario Explain, back up opinion
CW: Next Question
2.Will user notice action is available? Typical supporting evidence
Experience Visible device, such as a button Perceivable representation of an action such as a
menu item
CW: Next Question
3.Will user know it’s the right one for the effect? Typical supporting evidence
Experience Interface provides a visual item (such as prompt)
to connect action to result effect All other actions look wrong
CW: Next Question
4.Will user understand the feedback? Typical supporting evidence
Experience Recognize a connection between a system
response and what user was trying to do
Let’s practice
Library web site Users:
Student users, familiar with computers and libraries, but new to this web site
Task: find Don Norman books in library Click on Books, Catalog, Videos link Search by: choose Author Type “Norman, Don” and click Search Click on Norman, Donald link Click on design of everyday things link Write down call number and what floor its on
CW: Questions
1. Will users be trying to produce whatever effect action has?
2. Will users be able to notice that the correct action is available? (is it visible)
3. Once found, will they know it’s the right one for desired effect? (is it correct)
4. Will users understand feedback after action?
CW Summary
Advantages Explores important
characteristic of learnability
Novice perspective Detailed, careful
examination Working prototype not
necessary
Disadvantages Can be time consuming May find problems that
aren’t really problems Narrow focus, may not
evaluate entire interface
Your turn
Prepare: Describe users and their experience Determine task(s) and action lists
Evaluation: Choose the one you didn’t evaluate last time
As a group, for each action, answer the 4 questions with evidence
CW: Questions
1. Will users be trying to produce whatever effect action has?
2. Will users be able to notice that the correct action is available? (is it visible)
3. Once found, will they know it’s the right one for desired effect? (is it correct)
4. Will users understand feedback after action?