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Usability, Accessibility andUser Centered Design
Usability
David Lamas, Ilya Shmorgun
Tallinn University, 2012
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Usability
Today we will cover
Usability concepts
Usability evaluation Usability meytrics
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Usability
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Usability
According to the ISO
Usability is the extent to which a product can be
used by specific users to achieve predefined goals
with
Effectiveness,
Efficiency, and
Satisfaction in a specified context of use
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Usability
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Systemacceptabil ity
Socia l acceptab i l i ty
Pract ica l
acceptabil ity
Usefu lness
Util i ty
Usabi l i tyC o s t
Compat ib i l i ty
Reliabil ity
Memorabi l i ty
Learnabil ity
Efc iency
Satisfaction
Effectiviness
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Usability
In the system acceptability framework
Usefulness
Concerns the degree to which a product enables a user
to achieve his or her goals, and is an assessment of the
users willingness to use the product at all
Without usefulness, other measures make no sense,
because the product will just sit on the shelf
If a system is easy to use, easy to learn, and even satisfying touse, but does not achieve the specific goals of a specific user,
it will not be used even if it is given away for free
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Usability
In the system acceptability framework, Learnability relates to
How easy is it for users to accomplish basic tasks the first time theyencounter the design?
Efficiency relates to Once users have learned the design, how quickly can they perform
tasks?
Memorability relates to When users return to the design after a period of not using it, how
easily can they re establish proficiency?
Effectiveness is Expressed as an inverse measure of the number of errors, it relates to
How many errors do users make, how severe are these errors, and how easilycan they recover from the errors?
Satisfaction relates to How pleasant is it to use the design?
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Usability
Most usability professionals use their timeworking on eliminating design problems, trying tominimize frustration for users
But know that this is a difficult goal to attain for everyuser of your product
And unfortunately, usability is invisible
If something is going well, you dont notice it
You can only measure how unusable it is, how manyproblems people have using something, what theproblems are and why
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Usability
Common five reason for the delivery of less
usable products are:
Development focuses on the system
Team specialists dont always work in integrated
ways
Design and implementation dont always match
Target audiences change and adapt
Designing usable products is difficult
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Usability
Development focuses on the system
Unfortunately
Designers, engineers, and programmers have traditionally placedthe greatest emphasis on the activity component
And much less emphasis on the human and the context components
The relationship of the three components to each other has alsobeen neglected
There is an underlying assumption that because humans are so flexibleand adaptable, it is easier for them adapt themselves to the machine,than vice-versa
Developers have historically been hired and rewarded not for their inter-personal skills but for their ability to solve technical problems
Designers usually go about developing products for end users who weremuch like themselves
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Usability
Team specialists dont always work in integrated ways
To improve efficiency, many organizations have brokendown the development process into separate components
For example
the user interface
the help system, and
the written materials
There is nothing inherently wrong with specialization
The difficulty arises when there is little integration of these
separate components and poor communication among thedifferent development teams
Or when organizations unknowingly exacerbate this lack ofintegration by usability testing each of the components separately
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Usability
Design and implementation dont always match
The design of the user interface and the technical
implementation of the user interface are different
activities, requiring very different skills This distinction was rarely acknowledged in the past
Nowadays however, the challenge of design has increased
dramatically due to the need to reach a broader, less
sophisticated user population and the rising expectations forease of use
To use a computer analogy, the focus has moved from how it
works to how it communicates
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Usability
Target audiences change and adapt The original users of computer-based products were enthusiasts
possessing expert knowledge of computers
a love of technology the desire to tinker, and
pride in their ability to troubleshoot and repair any eventual problem
Designers and developers of these products shared similarcharacteristics
In essence, users and developers of these systems were one and the
same Not anymore!
Todays user is not even remotely comparable to the designers anddevelopers in skill set, aptitude, expectation, or almost any attributethat is relevant to the design process.
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Usability
Designing usable products is difficult
Part art, part science, it seems that everyone has anopinion about usability, and how to achieve it
This trivializing of usability creates a more dangeroussituation than if designers freely admitted that designing forusability was not their area of expertise and began to lookfor alternative ways of developing products
Everyone as an opinion until it is time to evaluate the
usability of a product Which requires
Operational definitions; and
Some kind of measures
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Usability
But why should we care about usability?
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Usability
But why should we care about usability?
Usability is a necessary condition for survival
There's no such thing as a user reading a manual or
otherwise spending much time trying to figure out an
application
There are plenty of other digital artifacts available
Leaving a website or dropping an application is the first line of
defense when users encounter a difficulty
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Usability
But why should we care about usability?
Even for a vertical audience
Usability is a matter of employee productivity
The time users waste being lost on your intranet or
trying to deal with a cumbersome application
is money being wasted by paying them to be at work without
getting work done!
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Usability
And when should we start worrying about it?
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Usability
And when should we start worrying about it?
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Usability evaluation
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Usability evaluation
Usability evaluation refers to the systematic
experimental evaluation of the interaction
between people and the products,
equipment, environments, and services they
use
It evaluates how easy a product is to use and
whether it is functional and acceptable
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Usability evaluation
It can be Formative focusing on
The most significant usability issues preventing users from completingtheir tasks
What works and what do users find frustrating
What are the most common errors or mistakes users are making
Assessing the improvements being made from one design interactionto the next
What usability issues are expected to remain after the product islaunched
Summative, focusing on Assessing the usability of a finished product; or
Comparing the usability of similar products, and in this case, questionsare normally about
How some specific usability goals where meet
How does one product compare against the competition
Assessing improvements from one product release to the next
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Usability evaluation
And it must be planned
User goals must be identified and tasks devised
Performance
Performance is about what a user does when interacting with
a product, it is about how useful, efficient, effective, learnable
and accessible a product is
Satisfaction
Its all about what a user says or thinks about her interactionwith a product
Usability metrics must be selected
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Usability evaluation
And it must be planned
Evaluation methods, settings, participants and
tools must be selected
Evaluation methods can be
Inspection based or empirical
Settings can be
The usability lab
Live, onsite
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Usability evaluation
And it must be planned
Evaluation methods, settings, participants and
tools must be selected
Evaluation methods can be
Inspection based or empirical
Settings can be
The usability lab
Live, onsite
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Usability evaluation
As for participants, They have a major impact on usability testing findings
It is critical that you plan how to include the most representativeparticipants as possible in your study
The steps you will go through in recruiting participants are essentially the
same whether you are collecting metrics or not If personas were used in de design process, then recruited participants should
fall within the perceived user group
Otherwise, a general profile should be outlined and the participants should berecruited accordingly
If a formative usability test is being run, a small number of participantsis required
Six are usually enough if no distinct user groups are foreseen, otherwise, eachgroup should have at least 4 members
If a summative usability test is being run, then the recommendednumber of participants number fall between 50 and 100
A valid test might still be run with 20 participants but results can be pale incomparison to running the test with a larger set of users
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Usability evaluation
Finally, as tools are concerned
They should be selected bearing in mind the data
cleanup and data analysis tasks ahead
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Usability evaluation
Anyway, while most of the usability attributes aremeasurable in some way... Making a product usable is never simply the ability to
generate numbers
While the numbers can tell us whethersomething works or not There is a distinctive qualitative element to how
usable something is which
is hard to capture with numbers; and is difficult to pin identify
has to do with how one interprets the data in order to knowhow to fix a problem because the behavioral data tells youwhy there is a problem
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Usability metrics
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Usability metrics
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UsabilityStudyScenarioX
typeofusabilitymetrics TaskSuccess TaskTime Errors Efficiency Learnability
Issuesbase
metrics
Self-reported
metrics
Behavioral
and
physiological
metrics
Combined
and
comparative
metrics
LiveWebsit e
metrics
Card-sorting
data
Completingatransaction X X X X X
Comparingproducts X X X X
Evaluatingfrequentuseof
thesameproductX X X X X
Evaluat ingnavigationand
informationarchitectureX X X X
Increasingawareness X X X
Problemdiscovery X X
Maximizingusabilityfora
criticalproductX X X X
Creat inganoverall
positiveuserexperienceX
Evaluatingtheimpactof
subtlechanges X
Comparingalternative
designsX X X X
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Usability metrics
Performance metrics Task success
Binary or graded Success or Failure
Complete success (with or without assistance), partial success (with orwithout assistance),
Time on task It is normally recorded for successfully accomplished tasks
Errors
Efficiency Normally a ratio between accomplishment and effort
Different authors have established context specific formulas that shouldbe accounted for before deciding on how to measure efficiency
Learnability Performance metrics collected over time on distinct product trials
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Usability metrics
Issues-based metrics What is an issue?
Anything that prevents task completion
Anything that takes someone off-course
Anything that creates some level of confusion
Anything that produces an error
Not seeing something that should be noticed
Assuming something is correct when it is not
Performing the wrong action
Misinterpreting some piece of content
Not understanding the navigation
How are they identified? Using an inspection method
Eventually combined with some performance data analysis
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Usability metrics
Issues-based metrics
After identified, issues usually classified according to theirseverity
Small impact on user experience, few users experiencing issue
Low severity
Small impact on user experience, many users experiencing issue
Medium severity
Large impact on user experience, few users experiencing issue
Medium severity
Large impact on user experience, many users experiencing issue
High severity
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Usability metrics
And others exist such as Self-reported metrics, used for assessing satisfaction
among other participant perceived measures
Behavioral and physiological metrics
of which eye-tracking is one of the most used ones as far as Webusability testing is concerned
Combined and comparative metrics based on combinations of the previously mentioned siblings
And others such as
Server logs Card-sorting data
Open card sorting
Closed card sorting
Accessibility indicators
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Usability metrics
However, it should be stressed that usability
evaluation results may not be valid unless the
conditions of the test closely match those of
actual product use
Therefore, the operating characteristics of the
prototype, the tasks, the duration of the test, and
the environmental conditions must be realistic Both extreme and typical conditions should be included
in the test
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Usability
Today we covered
Usability concepts
Usability evaluation
Usability metrics
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