Usability Goal Setting

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Usability Goal Setting
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How do we know weve succeeded?How do we
measure success?
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Usability Goal Setting

• Part of the Usability Engineering process
• Set by the design team on basis of selected
  usability criteria
• E.g. user satisfaction, user preference, ease of
  use (efficiency), learnability, memorability
• Includes all project stakeholders should
  participate

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Where in the Lifecycle?

• After User Analysis and User Profile
• After Contextual Task Analysis
• Feeds into user interface design tasks

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Phase 1
REQUIREMENTS ANALYSIS
User Profile Contextual Task Analysis Platform
Capabilities Constraints General Design
Principles
Usability Goals
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Purpose

• Help to focus and drive the design process
  (early)
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• Serve as acceptance criteria during usability
  evaluation testing (later in process).

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• On the cold morning of December 17, 1903, the
  Wrights' contraption chugged into a
  27-mile-per-hour headwind and lifted itself a few
  feet off the ground. Orville, who was at the
  flyer's simple controls, hadn't learned how to
  handle the machine yet, and he kept it aloft only
  12 seconds. The craft flew just 120 feet but
  soared into the history books. In those few
  seconds, the 19th century and its wind- and
  steam-powered surface transportation separated
  and fell away from the 20th century.

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Scope of Usability Goals

• Project dependent
• Team must decide on appropriate scope
• New product?
• Next version?

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Usability GoalsA Benchmark

• What do Usability Goals do for us?
• Make priorities explicit and visible
• Innovate for better usability
• Provide basis for tradeoff decisions
• Focus attention and resources
• Useful in design walkthroughs and throughout the
  entire product lifecycle

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• The X PRIZE is a 10,000,000 prize to jumpstart
  the space tourism industry through competition
  between the most talented entrepreneurs and
  rocket experts in the world. The 10 Million cash
  prize will be awarded to the first team that
• Privately finances, builds launches a
  spaceship, able to carry three people to 100
  kilometers (62.5 miles)
• Returns safely to Earth
• Repeats the launch with the same ship within 2
  weeks

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Usability Goals

• Components of a good usability goal
• Customer/user characteristics
• Task
• Metric
• Acceptance criteria

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Usability Goals

• 1. Identify customer characteristics from user
  personas
• Experience
• Exposure to system amount of training
• Education
• Attitude motivation

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Customer A white collar Netscape user for 4
years, uses the web daily, coming to our web site
for the first time
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Operational Definitions

• Define the user groups
• Novice
• Expert
• Casual
• Intermediate

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Usability Goals

• Ex Novice users (first time users) should take
  less than 2 minutes to search for price and
  availability information for a given product.
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• Ex Novice users (first time users) should find
  the specific product information faster and with
  less errors than with competitor application X.

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Usability Goals

• 2. Select a task from the task scenario
• Atomic or composite
• Relevant to customers task
• New concepts or mechanisms
• Critical features or mechanisms

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Task Determine the features of your low cost PC.
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• 3. Select a metric must be a measurable result
• Errors
• Interventions
• Time
• Reference used
• Percentage completed
• Indirect paths taken
• Satisfaction
• Preference

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• Where do we get these numbers?
• Metrics - compared against several different
  benchmarks
• Current level
• Minimum acceptable level
• Target level
• Optimal level

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Usability Goals

• Metric Can find the information in 2 minutes
  and give it at least an 8 on a satisfaction scale
  from 1 to 10.

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• 4. Select acceptance criteria
• Bounds for the metric (step 3)
• Number or percentage of times a single customer
  meets the criteria
• Number or percentage of customers who meet
  criteria

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• Acceptance Criteria to release At least 75 of
  all users are able to find information within
  metric.
• Nice-to-have Acceptance Criteria At least 90
  of all users are able to find information within
  metric.

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Priority Definitions

• How important is it to the final system
• Ex.
• Critical
• Required
• Depends on cost
• Desirable

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Exercise Team Meetings

• Break into teams
• Discuss deliverables for next class