Software Engineering I
Oct. 23, 2013

Users and their tasks

Introduce user-centered design

  How to create and evaluate designs to ensure usability
  Problem throughout SW history (50+ years)

  Need user-centered design

Focus on

  - Understanding users - system should match their knowledge level, abilities
    and preferences

  - Design SW based on understanding of the users' tasks

  - Make users involved in decision making process
     + Keep them involved throughout development

  - Design UI following good principles of usability
     + Use researched guidelines

  - Have users work with and get feedback on prototypes, online help, and draft
    user manuals

Focus on users in important because

  - Reduces training and support costs

  - Reduces time for users to learn the system

  - Greater efficiency of use

  - Reduces costs by developing only features that are needed

  - Reduces costs associated with changing the system later

  - Better prioritizes work for iterative development

  - Greater attractiveness of system = better sales and use

Characteristics of users

  - Goals for using system, what are they?

  - Potential patterns of use 
     + Too many steps makes SW cost too much time

  - Demographics - age, education, language, culture

  - Knowledge of domain and computers

  - Physical ability

  - Psychological traits and emotional feeling

Basics of UI design

  - Used to be simpler

  - Now an entire research field

  - Perform with other SW Engineering tasks

    + need some domain analysis and to define the problem
    + make 1st attempt at UI
    + Need use cases
 
  - Perform UI design iteratively

    + Use to refine use cases and UI
    + Paper prototypes 1st
    + Then "static" prototypes
    + Then functional prototypes

Analyze usability vs utility

   Utility - does it provide the right functionality?

   Usability - can the functionality be learned?

   Both are necessary

   Both are measured in context of different types of users

Usability includes

  Learnability - how fast can a user become efficient with the system
    + Is it intuitive?
  Efficiency of use - how fast can an expert user do work?
  Error Handling - abnormal situations
    + Error prevention
    + Error detection
    + Error correction
  Acceptability - how much users like the system

  Metrics exist for each of these

UI Terminology

  Dialog - back and forth interaction with computer
    Ex: Dialog box
  Control/Widget (a thing) - refer to components of UI
    Ex: menu, list, textbox, scrollbar
  Affordance - operations the user can perform at a given time by typing,
    clicking, or other commands
  State - UI state (stage of dialog)
  Mode - restriction on what UI can do
  Modal Dialog - restrictive mode in which user cannot interact with another
    window until the dialog has been dismissed.
  Feedback - response from system
  Encoding - format used to communicate information
    Ex: spoken language, text, font, icons, diagrams, photos, etc.

Usability Principles
  - Don't rely only on guidelines
    + Test with users
  - Base UI design on users' tasks as expressed in use cases
  - Ensure sequence of actions to complete a task is as simple as possible
  - Ensure user always knows what he/she can or should do next and what will
    happen when he/she does it
      + Gray out unavailable options
      + Use explanations
      + Make things stand out
        - Ex: bright/contrasting colors
  - Provide effective feedback and error messages
     - Progress bar for long operations
     - Inform user about current location in a series of windows
  - Ensure user can get out/go back/undo action or give a warning if they 
    cannot do so
     - Ex: Disk formatting
  - Ensure response time is adequate (warn on long waits)

More Usability Principles
  - Use understandable labels and other encodings
    - don't use technical jargon and acronyms unless necessary
    - use technical writers and graphic designers
    - use meaningful label names
    - use popup labels
  - Ensure UI appearance is neat and uncluttered
    - Don't give too much to look at at once
    - Messiness is bad
    - Only display essential information
      + provide methods for the user to get more info, if needed
    - Avoid having large numbers of dialogs
    - Highlight information that belongs together using boxes, colors, and 
      fonts
    - Put boxes around related items
    - Use horizontal lines to separate related items in a menu
    - Don't use too many different colors, fonts, or graphics
    - Line up labels and input fields so users can quickly read what needs to
      be entered
 - Consider needs of different groups
    - People from different locales
    - Persons with disabilities
    - Beginners vs. Experts
 - Provide help
 - Be consistent!

UI examples were provided in class, and poor features were pointed out.

Next up - Evaluating UIs
  - Heuristic evaluation
  - Usability defects
  - Usability inspections