Usability

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Usability

• Presented By Kenneth Frazier
• Diana Law
• Ngoc Bao Le
• May 30, 2002

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What is usability?

• One of the major areas of human-computer
  interaction (HCI)
• Involves the quality of the design,
  implementation, environment, and the match
  between the user and the system
• How does the design of the user interface affect
  usability?

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Definition of usability

• The capability in human functional terms to be
  used easily and effectively by the specified
  range of users, given specified training and user
  support, to fulfill the specified range of tasks,
  within the specified range of environmental
  scenarios.
• --Human Factors for Informatics Usability

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Definition of usability (contd)

• Brian Shackel suggested a more operational
  definition of usability where any system should
  have to pass the usability criteria of
• Effectiveness
• Learnability
• Flexibility
• User Attitude

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The Importance of incorporating usability

• When computers were first introduced, users were
  limited to computer professionals or specialists.
  Now, the users are much more diverse.
• Companies have been adding more features and
  functionalities to their products to attract
  users, making the products more complicated.

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Importance (contd)

• If consumers dont find a product usable, it may
  be abandoned.
• Usability plays a big factor in the
  competitiveness of products.
• Evaluating usability allows manufacturers to see
  how the product is doing in the market.

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Importance (contd)

• Usability is related to other software quality
  attributes
• Correctness
• Reliability
• Maintainability
• Learnability
• Understandability

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Usability Costs Benefits

• Importance of cost-justifying usability
• Costs more visible than benefits -gt managers
  reluctant to implement
• Benefits can potentially be multiple times
  greater than costs -gt need to illustrate
• Usability Professionals Association ranked
  cost/benefit analysis as top concern
• Companies with tight resources -gt need analysis
  to justify implementing usability engineering
  practices

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Cost Analysis

• Two major categories
• Initial Costs
• Sustaining Costs

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Initial Costs

• Usability Lab
• Many different types from single cubicle to
  multiple labs -gt depends on budget
• Range from cheap 1,000 to hundred thousands
• Video Recording Equipment
• Need to study subject in detail after testing
• Range from couple thousand and up, depends on
  quality of equipment

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Initial Costs (contd)

• Tools for Usability Engineering
• Prototyping Tools rapid prototype of UI,
  flexibility for change
• Cost 100 or more, but pays for itself easily in
  time saved to code up prototypes
• Observation Log Software record info during
  test (time, event, notes, etc)
• Cost 100 or more, also pays for itself
• User Activity Tracking keyboard mouse
  monitoring
• Very expensive to buy and upgrade, usually not
  needed

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Sustaining Costs

• Employees
• Experienced professionals worth extra cost
• Need 3-5 total
• Participants
• Questionnaire time, supplies (a few hundred
  dollars)
• Recruitment varies
• Compensation range from 10-120 per
  participant per evaluation
• Upgrades and Equipment
• New computers software, videotapes

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Benefits Analysis

• Numerous benefits, potentially exponential to
  costs
• One study found that an insurance company
  spending 500K on usability saved about 5
  million study by Nielsen
• Customers also benefit -gt more usable software is
  more USEFUL software

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Selling More of the Product (and Other Products)

• Difficult to quantify
• Compare increased sales projections
• Customer surveys why did they buy?
• Usability increasingly top priority for
  customers, gt price and features
• Higher priority than price company can raise
  price to cover usability costs
• Customer trust more usability shows the company
  cares

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Enhance Company Reputation

• Satisfied customers have brand loyalty
• More likely to buy other products from same
  company based on good 1st experience
• Influence 4 other people to buy same brand
• Dissatisfied customers much worse
• Much less likely to buy other products based on
  bad 1st experience, even if future releases
  promise improvements
• Influence 10 other people NOT to buy same brand

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Reduced Support Costs

• Average support call about 12 (includes
  duration, wage of support tech)
• Can easily multiply (one example 400K over six
  months)
• Increased usability less support costs
• Savings can be HUGE
• Ex Ford Motor Company fixed usability problems
  with internal software, support calls dropped to
  0 saved 100K (covered usability lab cost of
  70K)

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Prioritized Product Features

• Based on task analysis, customer field studies,
  and product usability comparisons
• Use info to prioritize reduce development costs
• Know what user really needs
• Not waste time developing seldom used features

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Other Benefits

• Save on internal product development
• Saves on development, saves in users
  time users time company time
• Reduced development costs
• Reduced training costs
• Reduced need for maintenance/updates
• Documentation training easier to develop

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Practices that address usability

• Companies that have put usability to use
• Microsoft Corporation
• Lotus Development Corporation
• Compaq Computer Corporation
• Apple Computer, Inc.

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Microsoft Corp.

• Began to see the need for usability in the
  mid-1980s
• All the teams have changed their development
  process since then.
• User-centered design and the Usability Group
• Case study engineering usability into Microsoft
  Word

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Lotus Development Corp.

• Lotus 1-2-3 spreadsheet application was
  criticized for being difficult to use.
• Management saw the importance of incorporating
  usability into their next release.
• As a result, 1-2-3 Release 4 was praised by both
  customers and press for its ease of use. It
  received several awards.

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Compaq Computer Corp.

• Compaq formed a group called the Human Factors
  Group.
• HF Group started out focusing on research that
  could help during the design phase
• Later, teams within Compaq saw the benefits of
  early HF involvement in the life cycle. The role
  of the HF Group expanded.
• Case study the Compaq Concerto

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Apple Computer, Inc.

• Apples culture made it easy to establish a
  usability program.
• The Apple HyperCard program was considered a
  breakthrough in technology but was difficult to
  use.
• The creation of a formal usability group,
  User-Aided Design Group, followed the success of
  the HyperCard usability study.
• Case study PowerBook 170

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Usability Testing Methods

• Definition making sure that people can find
  and work with the functions to meet their needs.
  (Dumas Redish)

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Usability Testing Characteristics

• Five characteristics that are common in a
  usability test
• Improve usability of product
• Participants are real users
• Participants do real tasks
• Participants actions (verbal non-verbal) are
  observed and recorded
• Test result data are analyzed to identify
  problems with product

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Importance of Usability Testing

• Focuses on identifying problems with a specific
  product
• Focuses on user needs and what makes products
  sell
• Detects global problems that exist in an
  organizations design and development processes

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Example Improving Processes

• Problem Users received system messages they did
  not understand
• Solution
• Instead of fixing just those specific messages,
  look for global problems in ALL messages
• Recommend rewriting all problematic messages
  not just those specific ones
• Results Developers see how certain message
  styles are problematic improved development
  process in composing messages

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Testing Methods

• Cognitive Walkthrough
• Heuristics Evaluation
• Task Analysis
• Prototyping

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Cognitive Walkthrough (CW)

• Designed to identify user thought process in
  order to develop the UI around it
• Used to evaluate the strengths and weaknesses of
  the interfaces without creating or using a
  prototype or design of the interfaces
• Efficient and effective way of assessing user
  interfaces when it is not feasible to produce a
  complete prototype of the interfaces

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CW Process

• One approach is having HCI experts as users
  walkthrough the design
• Users evaluate all possible actions by comparing
  their goals with expected outcome of actions
• Users then decide on the action
• When action is complete, users evaluate actual
  results to determine progress towards goals

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CW Process cont

• Technique
• Users answer questions regarding each decision
  they make
• Questions focus on helping users recognize their
  goals, results of their decisions, and progress
  toward goals

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CW Advantages and Disadvantages

• Advantages
• Makes user goals and expectations explicit
• Helps designers gain understanding of users
  wants, needs, expectations
• Identifies problems explicitly
• Disadvantages
• Tedious process lots of time, extensive
  planning
• Massive amount of paperwork up to 15 pages for
  a single user task

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Automated CW

• Uses computer-based program to make CW process
  easier
• Advantages
• Shifts focus from CW process to system problems
• Eliminates paperwork
• Helps organization of questions
• Easier to organize and plan

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Heuristics Evaluation

• Looks at an interface and come up with an opinion
  about what is good and bad about the interface
  (Nielsen Molich)
• Needs about 3 to 5 HCI experts to find about 98
  of usability problems
• How can one judge an interface being good or bad?
• Common sense intuition
• 9 heuristics rules created by Nielsen Molich

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Nine Heuristics Rules

• Simple and natural dialogue
• Speak the users language
• Minimize user memory load
• Be consistent
• Provide feedback
• Provide clearly marked exits
• Provide shortcuts
• Good error messages
• Prevent errors

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HE Advantages Disadvantages

• Advantages
• Takes 3 to 5 experts to identify most problems of
  system
• Cheaper than other methods
• Does not require advance planning
• Can be used early in development process
• Disadvantages
• Identifies problems but does not recommend
  solutions

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Task Analysis

• Focuses on
• Understanding what users tasks are
• Describing, identifying and observing tasks
  performed by users
• Hierarchical - can be iteratively broken down
  into multiple functions or tasks

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Task Breakdown

• Each task has
• An objective or goal
• A starting and stopping point
• An action or set of actions
• Skills or requirements needed to accomplish task

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TA Advantages

• Allows flexibility to gather specific data about
  a specific aspect of the system
• Example Gather data about a specific menu of
  system. Only need to test that menu, not the
  whole system
• Focuses on analyzing, identifying user task and
  goals helps system developments

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Prototyping

• Hands-on experience of system look-and-feel
• Used in early phase of development
• Users interact with UI prototypes on paper or
  computer
• Designers get early feedback
• Less development cost easier cheaper to fix
  now than later

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Prototyping Advantages and Disadvantages

• Advantages
• Provides more feedback from users
• Users more willing to be harsh if they see a
  rough prototype
• Easier to make changes
• Designers more willing to change design
• Disadvantages
• Designers have to waste time making prototype
  which may not be used
• Difficult to simulate real response time could
  mislead users about system performance