INFO3315 Week 4
Personas, Tasks
Guidelines, Heuristic Evaluation
Guidelines
For design and heuristics evaluation
Fine-grained guidelines
Easier for less experienced evaluators
Text guidelines
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Avoid negatives (sic)
Short simple sentences.
Active voice (not passive).
AVOID UPPER CASE
http://guidelines.usability.gov/
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Section 1, Make Action Sequences Clear
Section 2, Avoid Jargon
Section 3, Use Familiar Words
Section 4, Define Acronyms and Abbreviations
Section 5, Use Abbreviations Sparingly
Section 6, Use Mixed Case with Prose
Section 7, Limit the Number of Words and Sentences
Section 8, Limit Prose Text on Navigation Pages
Section 9, Use Active Voice
Section 10, Write Instructions in the Affirmative
Section 11, Make First Sentences Descriptive
Coarse-grained guidelines
Challenging for less experienced
evaluators
Heuristic evaluation
aka Usability Inspection
and guidelines
Nielsen’s original heuristics
• Visibility of system status.
• Match between system and real world.
• User control and freedom.
• Consistency and standards.
• Error prevention.
• Recognition rather than recall.
• Flexibility and efficiency of use.
• Aesthetic and minimalist design.
• Help users recognize, diagnose, recover from errors.
• Help and documentation.
http://www.nngroup.com/articles/ten-usability-heuristics/
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• Visibility of system status The system should always keep users informed
about what is going on, through appropriate feedback within reasonable
time.
– eg make visible the delay as a file is being loaded
– < .1 second instantaneous, < 1 second perceptible, > 1 second let user know
they need to wait
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Match between system and the real world The system should speak the
users' language, with words, phrases and concepts familiar to the user,
rather than system-oriented terms. Follow real-world conventions, making
information appear in a natural and logical order.
– eg use terms the user will understand
• User control and freedom Users often choose system functions by mistake
and will need a clearly marked "emergency exit" to leave the unwanted
state without having to go through an extended dialogue. Support undo
and redo.
• Consistency and standards Users should not have to wonder whether
different words, situations, or actions mean the same thing. Follow
platform conventions.
– Challenges of standards
• Error prevention Even better than good error messages is a careful design
which prevents a problem from occurring in the first place. Either
eliminate error-prone conditions or check for them and present users with
a confirmation option before they commit to the action.
• Recognition rather than recall Minimize the user's memory load by
making objects, actions, and options visible. The user should not have to
remember information from one part of the dialogue to another.
Instructions for use of the system should be visible or easily retrievable
whenever appropriate.
• Flexibility and efficiency of use Accelerators -- unseen by the novice user - may often speed up the interaction for the expert user such that the
system can cater to both inexperienced and experienced users. Allow
users to tailor frequent actions.
• Aesthetic and minimalist design Dialogues should not contain
information which is irrelevant or rarely needed. Every extra unit of
information in a dialogue competes with the relevant units of information
and diminishes their relative visibility.
• Help users recognize, diagnose, and recover from errors Error messages
should be expressed in plain language (no codes), precisely indicate the
problem, and constructively suggest a solution.
• Help and documentation Even though it is better if the system can be
used without documentation, it may be necessary to provide help and
documentation. Any such information should be easy to search, focused
on the user's task, list concrete steps to be carried out, and not be too
large.
Activity: Identify potential trade-offs
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Visibility of system status.
Match between system and real world.
User control and freedom.
Consistency and standards.
Error prevention.
Recognition rather than recall.
Flexibility and efficiency of use.
Aesthetic and minimalist design.
Help users recognize, diagnose, recover from errors.
Help and documentation.
Main stages of heuristic evaluation
• Preliminaries
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Agreed set of heuristics to use;
Programming team member overviews system;
And team member is available throughout;
Set of tasks;
Main stages of heuristic evaluation
• Evaluation:
– Each expert works independently through the UI;
– Team member records problems, so expert can simply
state them (single person works well, so they bring all
details together);
– Also answers any questions (eg expert gets stuck,
cannot find how to do a task, may need help with
domain expertise aspects)
– Multiple passes (overview, then detailed)
– Results in a set of identified failures to match the
heuristics (part of interface, violated heuristic)
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Main stages of heuristic evaluation
• Concluding summary
– Summarise all the flaws
– Rate these in terms of severity
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Severity ratings
http://www.nngroup.com/articles/how-to-rate-the-severity-of-usability-problems/
• “The severity of a usability problem is a
combination of three factors:
• The frequency with which the problem occurs: Is
it common or rare?
• The impact of the problem if it occurs: Will it be
easy or difficult for the users to overcome?
• The persistence of the problem: Is it a one-time
problem that users can overcome once they
know about it or will users repeatedly be
bothered by the problem?”
Severity ratings
http://www.nngroup.com/articles/how-to-rate-the-severity-of-usability-problems/
• 0 = I don't agree that this is a usability
problem at all
1 = Cosmetic problem only: need not be fixed
unless extra time is available on project
2 = Minor usability problem: fixing this should
be given low priority
3 = Major usability problem: important to fix,
so should be given high priority
4 = Usability catastrophe: imperative to fix this
before product can be released
Summarising the results
Description of problem
Heuristics violated
S1
S2
S3
Hard to find the Archive
button
Consistency …
0
1
2
Scroll bar not visible
Visibility…, Match system and real 3
world
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4
User has to remember ID from
last screen
Recognition rather than recall
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Interface uses language that is Match system and real world
not meaningful to user – select
bundle for student data
Instructions say “Circle all
Match system and real world
selections” but there are check
boxes
What does this graph tell you?
Shows which evaluators found which usability problems in HE of a banking system.
Each row is an evaluator (n=19) and each column is a flaw (n=16)
Black squares show where evaluator found the problem.
The rows are sorted with most successful evaluators at the bottom.
The columns are sorted with easiest to find problems at right.
http://www.nngroup.com/articles/how-to-conduct-a-heuristic-evaluation/
No. of evaluators & problems
19
www.id-book.com
Discount evaluation
• Heuristic evaluation is referred to as
discount evaluation when 5 evaluators are
used.
• Empirical evidence suggests that on
average 5 evaluators identify 75-80% of
usability problems.
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www.id-book.com
Critical to success
• Set of heuristics
• Set of tasks
• Prototype interface (can be story boards, so
long as they have enough of the key details)
• Experts!!!
Advantages
• No users
– No need to recruit users
– No ethical issues
• Low cost – “discount” with just 5 expert
evaluators
• Very useful for software developers
Disadvantages
• Relies on experts ….
– Callibre
– Biases
– Domain expertise
– Can be expensive
• Can find trivial problems that may not really
matter to actual users