Heuristic evaluation and guidelines - Current UG

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17 Νοε 2013 (πριν από 3 χρόνια και 8 μήνες)

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Heuristic evaluation

aka Usability Inspection

and guidelines

2

www.id
-
book.com

Heuristic evaluation


Developed Jacob Nielsen in the early 1990s.


Based on heuristics distilled from an empirical
analysis of 249 usability problems.


These heuristics have been revised for current
technology.


Heuristics being developed for mobile devices,
wearables, virtual worlds, etc.


Design guidelines form a basis for developing
heuristics.

3

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/


Visibility of system status

The system should always keep users
informed about what is going on, through appropriate feedback
within reasonable time.




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.




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.




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.

6

Activity: Identify potential trade
-
offs


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
.

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/

What does this graph tell you?

8

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.


9

www.id
-
book.com

No. of evaluators & problems


10

Main
stages
of heuristic
evaluation


Preliminaries


Agreed set of heuristics to use;


Programming team member overviews system;


And team member is available throughout;


Set of tasks
;


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)


Concluding summary


Summarise

all the flaws


Rate these in terms of severity


Critical to success


Set of
heurstics


Set of tasks


Prototype interface


Experts!!!


12

www.id
-
book.com

Advantages and problems


Few ethical & practical issues to consider because
users not involved.


Can be difficult & expensive to find experts.


Best experts have knowledge of application domain &
users
.


Best if experts are not the
designers.T


Biggest problems:


Important problems may get missed;


Many trivial problems are often identified;


Experts have
biases;


May encourage tinkering with the interface detailed in the
identified problems.

About heuristics

There are many options

The link between design and evaluation

Goals of INFO3315

Learn about the range of techniques to:


Understand users


Establish
requirements


Brainstorm alternatives creatively


Prototyping
alternative


Evaluate
these


Reflect
on strengths and weaknesses of
prototypes


Learn how to actually use a core set of these
techniques


High level heuristics

Harder for novices to use effectively

16

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/

Ben
Shneiderman's

golden rules for
dialogue


Consistency


e
g

location of “quit”


short
cuts for frequent users


informative feedback


HTTP Error 404 !!!


closure
in
dialogues


(
ie

clear when action is complete)


simple
error handling


easy
reversal of
actions


undo


support
internal locus of
control


Users should feel in control


reduce
short term memory load

Bruce
Togazzini


http://www.asktog.com/basics/
firstPrinciples.html


Anticipation


Autonomy


Color Blindness


Consistency


Defaults


Efficiency of the User


Explorable

Interfaces


Fitts
' Law


Human Interface Objects


Latency Reduction


Learnability


Metaphors, Use of


Protect Users' Work


Readability


Track State


Visible Navigation

Many other guidelines


Company specific


Device/OS specific


e
g

https://
developer.apple.com
/library/mac/docume
ntation/
userexperience
/conceptual/
applehiguideli
nes
/Windows/
Windows.html


ISO, ANSI Standards


National Standards


Military Standards


Accessibility Standards

M
ore
specialised

heuristics

Narrower than all interaction

(
eg

door opener)

21

www.id
-
book.com

Heuristics for websites focus on key
criteria
(Budd, 2007)


Clarity


Minimize unnecessary complexity & cognitive
load


Provide users with context


Promote positive & pleasurable user
experience


OS X Example


“mental model your users have should infuse the
design … support the user’s mental model by
striving to incorporate the following
characteristics


Familiarity


Simplicity


Availability
(functionality available)


Discoverability


https://developer.apple.com/library/mac/documentation/userexperience/conceptual/applehiguidelines/Intro/Intr
o.html#//apple_ref/doc/uid/TP30000894
-
TP6

(visited 2013)

Drill down


Class activity on heuristic calling for
Simplicity


What were things you discovered in your
Think
-
Aloud usability evaluations where you
discovered that you had failed to
do this.

Fine
-
grained guidelines

Easier for less experienced evaluators

Text guidelines


Avoid negatives
(sic)


Short simple sentences.


Active voice (not passive).


AVOID UPPER CASE



Note: CW Q2 relates to these


Tabletop heuristics


General heuristics


Shneiderman

(1992) Nielsen (1994)


Groupware


Baker et al. (2002)


Large screen Information Exhibits


Somervell et al. (2003) Czerwinski et al. (2006)



T
.
Apted,A
. Collins, and J. Kay. Heuristics to support design of new software for interaction at tabletops. In
CHI
’09
Workshop
on
Multitouch

and Surface Computing
, 2009
.


1. Design independently of table size

(e.g. easily resize interface elements)

2. Support reorientation

(support users working at any table position)

3. Consider human reach

(avoid unreachable, fixed interface elements)

4. Use large selection points

(support large input cursors/fingers)

5. Manage interface clutter

(quick removal/hiding of information; consider multiple users)

6. Use table space efficiently

(avoid modal
behaviour
, support private/group spaces)

7. Support private/group interaction

(usable as a private or shared resource)


How would one validate a set of
heuristics?

And how would you know about this?

How to select appropriate
heuristics?

Context

Validity

Usability (broad versus detailed)

Summary of HE


No users needed


Heuristics needed


Experts needed (NOT the designers…)


Relatively cheap