Revision for COMP5427
Usability Engineering Review
The whole semester and exam
Overview
• Concepts
– What do they mean
– Why do they matter
• Techniques
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What are they
When to use them
How to use them
Trade-offs
• Links between concepts, methods
• Use concepts to explain, justify aspects
Techniques you have practiced most
• Designing tasks
• Observing users
– Think-aloud
• Asking users
– Focus groups
– Comments made during think-aloud
• Predicting usability
– Heuristic evaluation (guidelines feed into design)
– Cognitive walkthrough
Other important aspects
• H&P wheel
• Contextual enquiry and ethnography
• Mental models, Norman's model, Fitts' Law,
Attention, Memory, Perception
• Questionnaires
• Accessibility
• GOMS in three parts: Part 1 | Part 2 | Part 3
Basic assessment of knowledge
of key techniques
Knowledge of a key technique
Q: State five of the most important things you need to do when you conduct a think-aloud usability
evaluation. For each, explain why it is important.
1.
Justification:
2.
Justification:
3.
Justification:
4.
Justification:
5.
Justification:
Detailed knowledge of practiced
technique
A colleague ran a think-aloud usability study where
Participant 5 became quite lost and spent 20 minutes just
trying anything at the interface, became flustered and
then gave up.
a) What improvement would you recommend in this
situation.
b) Why is this a better approach?
c) How would the results for this user be interpreted in
the case of your improved approach.
Knowledge of a key technique
Identify three important elements in conducting an effective Heuristic Evaluation (HE)
usability assessment. For each, explain why it is important.
1.
2.
3.
Guidelines and design
• It is recommended that designers should use colour
sparingly, avoiding any more that 5 different colour codings.
Explain how this is related to the limitations of human
working memory.
• While colour in interfaces has benefits, some people are
colour blind. Explain how extensive this problem is, by
stating the proportion of people affected by colour
blindness.
• Explain how you can still make use of colour but take
account of the needs of people who are colour blind.
• Explain how this affects the broader population.
• Explain how accessible guidelines would influence your
design of an interface that makes use of a brightly coloured
image as a link.
Critique, enhance, evaluate
many nice examples from http://baddesigns.com/examples.html#soupspoon,
http://hallofshame.gp.co.at/,
Consider this dialogue box that appeared in a game if the user
attempted to quit without saving the game.
• Annotate it to show one important problem.
• State which of Nielsen’s heuristics that is violated by this
aspect of the design.
• Draw an improved version in the space below.
• Annotate it to show how it improves on the design above.
Your annotations should refer to relevant design principles.
Concepts and links
Lectures introduced the notion of mental models. Explain how they
relate to each of the usability techniques you studied during the
semester.
Explain why many desktop interfaces designs include blinking for
cursors.
Explain why it is generally recommended that screen elements should
not blink. Your answer should refer to human factors affecting design.
What is the relationship between Fitts' Law and the GOMS
assumptions you need to make about the value of P.
Methods linked
Suppose you are planning the usability evaluation of the
interface you designed in your project. A colleague has
proposed the techniques shown below. Critique each in terms of
the strengths and weaknesses of the proposed techniques, for
use at the time and stage described. In your answer refer to the.
• Low fidelity prototype 1: evaluated with Think-Aloud
with 10 first year university students.
• First implemented prototype: evaluated with Cognitive
Walkthrough
• Second implemented prototype: evaluated with GOMS
Bringing all elements together
• Consider the interface below where the user wants to find out about gift certificates.
• Explain how Fitts’ Law informs you assessment of the usability of this form of
hierarchical menu.
• Explain how you would improve this design.
• Then assuming a user comes to the initial screen, conduct a cognitive walkthrough.
Bringing all elements together
Background:
The FitBit is a device that tracks physical activity.
Consider ways to make use of the data from the FitBit device to
help people improve their health.
physical activity
Inactivity
Sleep
Consider this UI:
A user can view their data at an interface like that shown below.
In this case, the user has moused over the bar representing their
activity from 11.15 – 11.30.
This shows that the user walked 792 steps in that 15 minute period.
Suppose the team that created this interface had written the following
one sentence statement.
The long term FitBit interface will enable first time users to quickly and
easily determine how active they have been over a day.
Annotate it to show the key parts and to show improvements.
Suppose you are in a team that aims to improve this UI.
You have been asked to conduct a usability study.
Write one abstract task and 5 matching concrete tasks to use in this
process.
Critiquing the tasks
Explain your design of each task in terms of the
following aspects.
• Effectiveness and coverage
• Concreteness.
• Understandable for the user.
• Avoids leading the user.
• Suppose you are designing the tasks for a think
aloud usability evaluation, to assess whether
users can make effective use of this interface to
assess their level of inactivity.
• Consider the following task:
Use your mouse to hover over the tallest bar in
the chart to see how many steps this user took at
that particular time?
• State one important weakness in this task
• Write a better version of question that avoids this
weakness.
For a break, do the USE survey
http://www.sydney.edu.au/itl/feedback/survey
New consider a pervasive display
created by a team of students
This aims to help people log their
levels of INactivity, somewhat similar
to our food logger
Suppose you are in a team that created the following Powerpoint first
prototype for the project. The left screen (i) is the initial state of the
interface. The middle one (ii) shows what happens when the user
touches “6-8 hours”; that part of the display changes colour to give the
user feedback. The right figure (iii) shows the screen when the user
lifts their finger. They can see their average logged sitting hours for the
last week and month. These stay on the screen for one minute. After
that, the screen goes back to the initial state.
• Write one well-designed concrete think-aloud
task for testing this prototype.
• Explain how it is well designed in terms of
concreteness.
Your answer should include an example of a
version of the task that is poor on this criterion
and you should explain why this is so.
• Explain how it is well designed in terms of
avoiding leading the user.
Your answer should include an example of a
version of the task that is poor on this criterion
and you should explain why this is so.
• The design has not dealt with user errors. List
one of the most important such user errors.
Then describe how you would design the
interface to address it.
• Prototypes are characterised as low to high
fidelity (lo-fi to hi-fi). State where this design
fits. Justify your answer.
• Explain why it is useful to create multiple lo-fi
prototypes early in the project.