Introduction to Usability Design of Software Applications

1. Usability Design of
Software Applications

2. Introduction to Usability Design of
Software Applications
► Usability in software engineering refers to the levels to which a design can be
used by a certain number of users to attain the set objectives with efficiency,
effectiveness and high-level satisfaction in a particular context. It is important to
carry out software usability so that you can determine if the product meets its end
goals and offers high level satisfaction to the users. It is a process you can do alone or
allow other testers to help you.
► Software usability refers to the controlled element of user experience design
that makes sure that users do not face problems when using a website's user
interface or product. A designer has the ability to control user interface,
usability, control accessibility and information architecture to match the
uncontrolled elements such as user lifestyle, objectives and habits. What you
need to know is that UX design usually makes use of the controlled elements of
technology to fit the uncontrolled aspects.

3. Introduction to Usability Design of
Software Applications
► In overall, usability testing software is the level of ease with which web
applications or software can be applied to attain the set goals efficiently and
effectively. The challenges involved in the use of the interface are assessed in
the process. Software usability relates to the functionality of the product or web
application.

4. Background on Usability Engineering
Types of variables and data
Data and statistics:
∙ This week we will cover background information about data and statistics that you will
have to use in the next weeks
∙ We are now going to look at:
-What qualitative and quantitative data we should collect in usability studies
-How we collect it
-How we analyse it

5. Background on Usability Engineering
Independent and dependent variables
► Dependent variables: things you measure, as success rate, number of errors, user
satisfaction, completion time
► Independent variables: things you can manipulate, as the testing conditions (e.g.,
interfaces, browser, monitor)
► Dependent variables represent an output or effect (what you plan to measure)
► Independent variables represent inputs or causes, or are tested to see if they
represent the causes of a phenomenon (What you plan to manipulate)

6. Background on Usability Engineering
∙ Both independent and dependent variables can be measured using 4 types of
data:
o Nominal
o Ordinal
o Interval
o Ratio

7. Background on Usability Engineering
Nominal data
o Nominal data are unordered groups or categories (e.g., male/female)
o These are typically independent variables that allow you to segment your data in different
groups.
o Nominal data is often analysed with simple descriptive statistics such as counts and
frequencies
o You could identify:
-The number or percentage of male vs female users
-The number or percentage of users who completed a task
-The number or percentage of users who have used a system before

8. Background on Usability Engineering
Ordinal Data
o Ordinal data includes ordered groups or categories
o The intervals between measurements are not meaningful
- e.g. excellent, good, satisfactory, adequate and poor("Likert scale")
- on a Likert scale, the difference between 1 and 2 is not necessarily the same as
the difference between 3 and 4
o Ordinal data is commonly analysed by looking at frequencies
o You could identify:
-The percentage of visitors of a web site who had a good or excellent experience

9. Background on Usability Engineering
Interval data
o Interval data is similar to ordinal, but intervals are equally split and there is no natural zero
point
► e.g. temperature,or the system usability scale (http://en.wikipedia.org/wiki/System
usability scale)
o Interval data allows to calculate a wide range of descriptive statistics (including averages
and standard deviation)
o You can typically distinguish ordinal from interval data by evaluating whether a point
► halfway between any two of the defined data points make sense
► If it does the data is interval data

10. Background on Usability Engineering
Ratio data
o Ratio data is similar to interval data, but the zero value is not arbitrary
► -e.g., time, height, weight
o Interval data can be analysed with the same techniques used for ratio data

11. Users and Principles

12. Understand the Users
It is important to know who the user is
► Work experience
► Computer experience
► Age
► Education
► Reading skills
► Language skills
► Work environment
► Task frequency
► … many more possibilities
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13. Design Principles
► Visibility
► Feedback
► Constraints
► Mapping
► Consistency
► Affordance
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14. Usability Principles
► Visibility of system status
► Match between system and the real world
► User control and freedom
► Consistency and standards.
► Help users recognize, diagnose and recover from errors
•Error prevention
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15. Usability Principles
► Recognition rather than recall
► Flexibility and efficiency of use
► Aesthetic and minimalist design
► Help and documentation
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16. Nine Golden Usability Principles
1. Build a UI that is consistent
• Design in, then evaluate
• Changes break consistency …
2. Design usable and discoverable shortcuts
• Users must be able to find them
• Users must be able to remember them
3. Provide appropriate feedback
• Not just error messages
4. Yield closure
• Have a clearly defined end-point in the interaction
5. Provide appropriate error handling
• Clearly tell users what was wrong
• Only make users redo the part that was wrong
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17. Nine Golden Usability Principles
6. Allow users to undo all actions
► If the operation cannot be “undone,” use hesitation
7. Put the user in charge
► Inexperienced users may be intimidated when the software makes
decisions
► Experienced users want to control the flow
8. Reduce the STM load
9. Design for the USER
► First
► Last
► Then test it
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18. Preventing Errors
► People often make mistakes
► Faster computers can increase errors
► Prevention strategies :
► Flow : Users make fewer mistakes when the flow through the UI makes sense
► Education : Better error messages can reduce errors
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19. Software Seatbelts
► The software can prevent the user from making dangerous choices
► If the dangerous choice must be available, allow it with a hesitation (“are you
sure?”)
► Exiting editors with changed, unsaved text
Should not hesitate if unchanged!
► Unix: rm *.o … rm * .o
rm –i *.o forces hesitation (alias rm “rm –i”)
► Omit menu choices that should not be used
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20. Software errors
► In software engineering, any deviation or mismatch occurring between the
expected or desired output of the software product is known as a software
error.
Types of software errors
1. User interface errors
These are the error which generally appears during the interaction of the user
with the system or when a user is using & handling a software product. It may
include the following errors: Missing or wrong functionality. Spelling, actual and
context error.
• No backup facility or revert function.
• Slow and poor responsive feature.

21. 2. Error handling errors
► A type of error where a system fails to predict the presence of an error and
lacks in safeguarding the system against it.
► • Lack of protection features from the malicious attacks. Inability to report
an error.
► Termination of task containing an error. Inefficiency in dealing with the
inappropriate inputs by users.

22. 3. Control flow errors
► Errors with respect to passing on the control of the program, in a wrong
direction where software program behaves unexpectedly in the next step of
the execution.
► Presence of in infinite loop.
► Unlimited wait for the invalid condition or loop.
► Backtracking to a wrong state or place. Reporting syntax error during the run-
time, etc.

23. 4. Calculation error
► Errors, arising from the calculation mistakes.
► Incorrect implementation of the computational logic.
► Mistakes in using the operators.
► Lack of precision in the calculation.
5. Race condition
Errors arising due to initiation of the next task without the termination of
the previous task, as such pre-requisites for the second task, has not been
met in this condition.

24. 6. Load condition
► The errors that occur due to the non-availability of resources, insufficient
memory to accommodate the large size of data.
7. Testing errors
It involves the errors occurred while implementing and executing the testing
process such as in documentation, methods followed, and in reporting.
-Unable to execute a test plan.
-Failure in exploring the bugs.
-Inefficiency in reporting a bug or a defect.
-Corrupted test data files

25. 8. Hardware error
► Non-availability & non-compatibility with the device.
► Incorrect address of the device.
► Inappropriate or incorrect paging process.
► Wrongly fetching & interpreting the instructions.
► Time-out issues.

26. Psychopathology
● It is the study of abnormal cognition, behaviour and
experiences which differs according to social norms and rests upon a
number of constructs that are deemed to be the social norm at any
particular era.
● Psychopathology formalizes basic concepts and principles of design
from observations of everyday objects. Why some objects, as simple as
doors, please their users while others frustrate them.
● Design is concerned with how things work, how they are controlled,
and the nature of the interaction between people and technology.

27. Contd….
● Two of the most important characteristics of good design are
discoverability and understanding.
● When done well, the results are brilliant, pleasurable products.
When done badly, the products are unusable, leading to great
frustration and irritation.

28. Principles
1. Provide a good conceptual model.
A good conceptual model allows us to predict the effects of our
actions.
Simply knowing the relationship between the controls and the
outcomes.
2. Make things visible.
A device is easy to use when there is visibility to the set of possible
actions, where the controls and displays exploit natural mappings.

29. Contd..
3. The principle of mapping.
● Mapping is a technical term meaning the relationship between two
things, in this case between the controls and their movements and the
results in the world.
● Natural mapping (taking advantage of physical analogies and
cultural standards) leads to immediate understanding.
● Natural mapping is a natural association & relation between two sets
where one can be a controller & the other can be an object.”
● A good natural mapping can make your life easy & peaceful
whereas bad natural mapping can lead to confusion and frustration.

30. example of Poor Natural Mapping i.e.
A Switchboard in my friend’s room.
Bad mapping is evident in the first picture, the Left Switch controls
a fan to the right whereas the Right Switch controls a fan to the left.
In good natural mapping, the Left Switch would control a fan to the
left and Right Switch would control a fan to the right, as illustrated
in the image shown in the second picture.

31. example is Stove Control
Figure (A) is an example of Bad natural mapping, where there is no clear mapping between
the controls and burners of the stove, i.e burdening the consumer to put extra effort into
learning and memorizing the controls. You can’t easily identify which control will operate the
Top-Left burner.
Figure (B) & (C) are examples of Good natural mapping, you can easily identify the
controller for each of the burners on the stove without thinking much, magical mapping! In
both illustrations, the arrangement of the controls is aligned with their respective burners on
the stove.

32. 4. The principle of feedback.
Feedback is sending back to the user information about what action actually has
been done, what result has been accomplished.
Feedback—sending back to the user information about what action has actually
been done, what result has been accomplished—is a well known concept in the
science of control and information theory. Imagine trying to talk to someone
when you cannot even hear your own voice, or trying to draw a picture with a
pencil that leaves no mark: there would be no feedback
Example :
A modern telephone and a old telephone
Modern telephone have more features and less feedback as compared to old
telephone.
(Refer The Design of Everyday Things, Don Norman, Pg No:27).

33. Making Mistakes
● Mistakes occur when a user has developed a mental model of the
interface that isn’t correct, and forms a goal that doesn’t suit the situation
well. If an error is possible, someone will make it.
● When someone makes an error, there usually is good reason for it. If it
was a mistake, the information available was probably incomplete or
misleading. The decision was probably sensible at the time.
●If it was a slip, it was probably due to poor design or distraction. Errors
are usually understandable and logical, once you think through their
causes.

34. Making Mistakes Contd…..
● The designer must assume that all possible errors will occur and
design so as to minimize the chance of the error in the first place, or its
effects once it gets made.
● Errors should be easy to detect, they should have minimal
consequences, and, if possible, their effects should be reversible.
● Errors are usually understandable and logical, once you think
through their causes. Don't punish the person for making errors. Don't
take offense. Try to design the system to allow for errors. Design so
that errors are easy to discover and corrections are possible.

35. GROWTH MINDSET
● Designer has a mindset that helps them grow individually. Their attitude and thinking
empowers, motivates, and elevates the people around them.
● A growth mindset is ready to embrace the positive evolutions as well as harder hitting
truths.
● Designers with a growth mindset can control their emotional state when it comes to
design critique.
● When on the receiving end of a tough design critique, they see it as a chance to
improve their fundamental design skills.
● They see feedback as a response to behaviour they’ve exhibited, not as an attack on
them. They just see it as it is, and work their way towards being better.

36. Mental Models
● Mental models, our conceptual models of the way objects work, events take place, or
people behave, result from our tendency to form explanations of things.
● These models are essential in helping us understand our experiences, predict the
outcomes of our actions, and handle unexpected occurrences.
● We base our models on whatever knowledge we have, real or imaginary, naive or
sophisticated.
● Mental models are often constructed from fragmentary evidence, with but a poor
understanding of what is happening, and with a kind of naive psychology that postulates
causes, mechanisms, and relationships even where there are none.
● Everyone forms theories (mental models) to explain what they have observed.
● In the absence of feedback to the contrary, people are free to let their imagination run
free.

37. Three different aspects of mental models must be distinguished: the design
model, the user's model, and the system image (figure 7.1).
Aspects of Mental Models

38. ● The design model is the conceptualization that the designer has in mind.
The user's model is what the user develops to explain the operation of the
system.
● Ideally, the user's model and the design model are equivalent. How ever,
the user and designer communicate only through the system itself: its
physical appearance, its operation, the way it responds, and the manuals
and instructions that accompany it.
● Thus the system image is critical: the designer must ensure that
everything about the product is consistent with and exemplifies the
operation of the proper conceptual model.
● All three aspects are important. The user's model is essential, of course,
for that determines what is understood. In turn, it is up to the designer to
start with a design model that is functional, learnable, and usable.

39. Helping Users Choose Action
The basic idea is simple. To get something done, you have to start with some notion of
what is wanted—the goal that is to be achieved. So there are four different things to
consider: the goal, what is done to the world, the world itself, and the check of the
world.
Action cycle
Human action has two aspects, execution and evaluation.
•The Gulf of Execution refers to the process of figuring out what an object does and
how to use it. This can happen either before using the object or while trying it out.
Affordances, signifiers, and mapping are tools designers use to help users bridge this
gulf.
•The Gulf of Evaluation occurs after using an object and refers to the process of
evaluating what the device did and whether that action matched our goals. Feedback and
accurate mental models are the most helpful tools for bridging this gulf.

40. Seven stages of action: one for goals, three for execution, and three for evaluation.
• Forming the goal
• Forming the intention
• Specifying an action
• Executing the action
• Perceiving the state of the world
• Interpreting the state of the world
• Evaluating the outcome
Example:
1.Goal: I need to go grocery shopping.
2.Plan: Should I drive to the store or take the bus?
3.Specify: I think I’ll drive.
4.Perform: I’ll follow the usual route to the store instead of a new one.
5.Perceive: Everything went smoothly and I’ve parked at the store.
6.Interpret: This means I can now go inside and shop.
7.Compare: I’ve met my goal of going grocery shopping!

41. Error Messages
●An error is defined simply as an action being performed by a user
who does not enter the request in a form the computer can
understand.
●The error message occurs when the system can’t interpret the
information given to it.
● Many systems try to prevent errors by requiring confirmation
before a command will be executed, especially when the action will
destroy something of importance. But these requests are usually ill-
timed because after requesting an operation, people are usually
certain they want it done.

42. Error Messages Contd…
● Errors come in several forms. Two fundamental categories are
slips and mistakes.
● Slips result from automatic behaviour, when subconscious
actions that are intended to satisfy our goals get waylaid enroute.
● Mistakes result from conscious deliberations.
● The same processes that make us creative and insightful by
allowing us to see relationships between apparently unrelated
things, that let us leap to correct conclusions on the basis of partial
or even faulty evidence.

43. People Expect Simplicity
● Humans have limited capacities for processing information and
often choose the path of least effort, even though an alternative
path would result in better outcomes.
● All decisions people make require mental effort. Every decision,
large or small, costs us time and effort.
● Combining different feature interactions causes even more
complexity and difficulty for users to form a mental model of
what’s happening with the system.

44. People Expect Simplicity Contd..
● Displaying a high number of options makes the screen appear
more crowded and the menus more complex.
● Adding features that have little to no value to most users
undermines people’s innate abilities to collect and process
information efficiently. Keeping the number of options at a
reasonable level allows people to make decisions more easily
and complete tasks faster.

45. Syntactic Signals
The UI design must explicitly indicate what should be done
- Physical or syntactic constraints limit our actions
- Affordances of controls-that is, the controls look familiar.
- Down arrows look like drop downs.
- "B" looks like bold face.
- If the UI design matches the user's mental model and offers good controls, users will
not need help.

46. Applications
Doors
Dozens of ways to open doors . A sign on a door that tells us how to open it is a very short
instruction manual.
The below are photographs of hardware for doors that open by being pulled.

47. Doors
- The large plates at the left are a signal to push, but in fact the door is
supposed to be pulled: no wonder the door needs the signs.
- The simple U shaped brackets below is a much better design, but they are
ambiguous enough that a sign still seems to be needed.
- Contrast with the two handles at the top, neither of which needs a sign yet is
always operated properly. If a door handle needs a sign, then its design is
probably faulty.

48. How to make non-confusing doors ?
Norman explains two principles of design that make objects, including doors,
more intuitive to use.
1. Discoverability
It means that just by looking at the door, you should be able to what you could
do with it. So a door with only a flap would be more intuitively interpreted as
something you push on rather than pull.
2. Feedback
A well-designed product should also provide you feedback while using it.
Feedback is some sort of indication that something happened. It tells whether
there was a change or not, or whether your action succeeded or failed. In the case
of doors, the twistable knobs would signal to you whether the door is locked or
not.

49. PROBLEM WITH SWITCHES
Switches have two basic problems
1.Which switch controls which function (grouping) ?
2. Which switch controls which device (mapping)?