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====== CS 352 ======

===== Project =====
  * [[project/start]]

===== HCI =====

==== What is HCI? ====
Human-computer interaction is: "concerned with the design, evaluation, and implementation of interactive computing systems for human use and with the study of major phenomena surrounding them" (ACM SIGCHI).

Other definitions:

  * Optimizing user's interaction with system, environment, or product.
    * How do we bring tech. in line with user expectations?

==== Usability Engineering vs. Interaction Design ====

Interaction design definition: Designing interactive products to support people in their everyday and working lives.

Usability engineering definition: Nielson doesn't really give one. It's a solid process by which you can create usable software.

==== Active Areas of  HCI ====

  * Novel interfaces/techniques.
  * Design & design practices.
  * Communication.
    * How medium affects the message.
  * Accessibility & universal computing.
  * Work efficiency.

==== Why should we care? ====

  * Computers affect most people:
    * 89% of US has access to computers. 65% are online.
    * Have to deal with businesses and gov't agencies.
  * Computers are everywhere.
  * Success often depends on ease of use more than power or features.

==== Case for HCI ====

  * Nielsen
    * Increase learnability.
    * Increase efficiency.
    * Increase memorability.
    * Decrease errors.
    * Increase satisfaction.
  * Preece
    * Utility?
    * Effectiveness?

==== User Experience Goals (Preece) ====

Preece introduces user experience goals:

  * Satisfying.
  * Enjoyable.
  * Fun.
  * Entertaining.
  * Helpful.
  * Motivating.
  * Aesthetically pleasing.
  * Supportive of creativity.
  * Rewarding.
  * Emotionally fulfilling.

Are these always good/desirable?

  * Depends upon the application.
  * E.g. emotional fulfillment in Excel.


==== Case Against Usability ====

There are places where usability may not be good:

  * Security systems.
  * Medicine (e.g. medicine bottles).
  * Complex system operators (make it too easy -> operator stupidity).

Examples of poor usability:

  * Home electronics with the only controls being the remote. (Lose the remote and get hosed.)
  * Scientific calculators/too much functionality in too little space.
  * QWERTY for English.

===== Evolution of Usability =====

==== History of Computer Interaction ====

=== 40s-50s: Batch ===
  * Computer performed one task at a time.
  * No interaction once computation started.
  * Switches, wires, punch cards, and tapes for I/O.

=== 60s-70s: Command line ===
  * Computers hit "big business."
  * More varied tasks.
  * Text processing, email, etc.
  * Teletype terminals.

=== 80s-present: WIMP ===
  * (Windows, Icons, Mouse, Pointer)
  * Computers in the home, everyday tasks, no training.
  * From multi-user to multitasking systems.
  * WIMP interface allows you to do several things simultaneously.
  * Has become the familiar GUI interface.

==== People in Computing History ====

=== Innovator: Ivan Sutherland ===
  * SketchPad -- 1963 -- first interactive drawing program on computer.
  * Hierarchy.
  * Master picture with instances.
  * Constraints.
  * Icons.
  * Copying.
  * Light pen input device.
  * Recursive operations.

=== Douglas Engelbart ===
  * Invented mouse/pointer.

==== Paradigm: Direct Manipulation ====

You are interacting with the image on the screen.

  * '82 Shneiderman describes appeal of rapidly-developing graphically-based interaction.
    * Object visibility.
    * Incremental action and rapid feedback.
    * Reversibility encourages exploration.

==== Paradigm: Metaphor ====

Metaphor paradigm involves mapping the real world onto computer use.

  * All use is problem-solving or learning to some extent.
  * Relating computing to real-world activity is an effective learning mechanism.
    * File management on office desktop.
    * E.g. financial analysis as spreadsheets.

===== Project =====

==== Library Field Trip ====

  * Going to learn how to watch people, environment, etc.
  * Learn how to take notes.

==== Proposal ====

  * Find a usability problem.
  * Research problem.
  * Create a proposal.

==== Research ====

  * 

===== Usability and Design Process =====

==== Basic Questions ====

  * What is usability in terms of design/requirements?
    * It's essentially the same thing, come at from different angles.
    * HCI from user standpoint, software engineering from developer's standpoint.
  * When and where in design/build process do you use usability?
    * Everywhere.

==== User-Centered Design Process ====

  - Identify users
  - Identify activities/contexts.
  - Identify needs.
  - Derive requirements.
  - Derive design alternatives.
  - Build prototypes.
  - Evaluate prototypes.
  - Iterate.
  - Ship, validate, maintain.

=== Understanding Users ===

  * Need to take into account:
    * Who users are
    * What activities are being done
    * Where interaction takes place
      * Conditions may exclude or require certain interface choices, e.g. use of sound.
  * Need to optimize interactions users have with a product.
    * Such that they match user activities and needs.

=== Understanding Users (2) ===

Who are the users?

  * Those who interact directly w/ product.
  * Managers of direct users.
  * Receivers of the product's output.
  * Purchasers of the product.
  * Users of competitor's products.

=== Populations and Sampling ===

  * Identify user groups.
    * Make sure all are represented in your study.
    * Make sure more than one person from each group is represented in your study.
  * How much to study?
    * Time.
    * Subjects.
  * Random vs. non-random sampling.

=== Studying Users ===

Each method of learning about users will be more appropriate depending upon the context.

  * Questionnaires.
    * Difficult to create in unbiased way.
    * Reach lots of people quickly.
  * Interviews.
    * Time-consuming.
    * Noisy analysis.
    * Can reveal information you didn't think of.
  * Focus groups.
    * Various levels of structure.
    * One person can dominate.
  * Naturalistic Observation
    * Ethnomethodological.
    * Contextual inquiry.
    * Participatory design.
  * Documentation.

=== Naturalistic Observation ===

== What are needs? ==

  * Users often don't know what's possible.
  * Users can't tell you what they need to achieve goals.
  * Instead, look at existing tasks:
    * Context
    * Information required
    * Collaboration
    * Why it's done that way
  * Envisioned tasks:
    * Can be rooted in existing behavior.
    * Can be described as future scenarios.
  * Based upon observation, design a system that meets user's needs in a great way.

== Ethnography ==

  * "Writing the culture."
  * Ethnographer takes part in the world for extended periods of time, passive observer.
    * "World" => company, society, family, etc.
  * Observe everything taking place: Activities, environments, interactions, practices, etc.
  * Hidden assumption: We don't always know what we know or do, make the implicit explicit.
    * Not limited to any particular scope.
    * Gather info on all observations.
  * Noisy, but very rich and detailed data.

  * Two types: Participant observation and Contextual inquiry.
  * Participatory Observation
    * "Going native"
    * Ethnographer part of culture.
    * May be difficult to relate back.
    * May influence outcome.
    * Tries not to make judgements about why events happen.
  * Contextual inquiry
    * Ethnographer less embedded in the culture.
    * Apprentice relationship to actor.
    * Some observation followed by questions to the actor to clarify meaning.
    * Tends to get more focused data.
    * Prone to rationalizations and tall tales.
      * When have to explain/vocalize, actor may come up with a story.

  * Problems with ethnography.
    * Data is very disorganized.
      * Difficult to know what to do with it.
      * Needs further refinement before it can be applied.
        * Use cases
        * Scenarios
        * Task analysis
        * Workflow models
    * Ethnogaphy often good starting point, but rarely self-sufficient.

== Observation ==

  * Subject knowledge/consent.
    * Public vs. private places.
    * If the observee has expectation of privacy, you must have consent.
  * Medium
    * Notebook
    * Audio tape
    * Video/photographs
      * Puts people less at ease. (=> modifies behavior to some extent)
  * Transcription
    * Within 24 hours.
    * Cleaned up version of notes.

===== Ethics =====

==== Learning Objectives ====

  * Discuss ethical concerns.
  * Role of IRB.
  * Principles and origins of Belmont report.
  * Principle of informed consent & considerations surrounding.
  * Responsibilities to participants before, during, after study.

==== History ====

  * Nuremberg doctor trials.
  * Milgram obedience experiments.
  * Thalidomide study.
  * Untreated syphilis study.
  * Human radiation experiments.

=== Nuremberg doctor trials ===

    * Nazi physicians charged conducting inhuman experiments on civilians and prisoners.
    * High altitude experiments:
      * 40% participants died.
    * Parachuting into cold water.
      * 30% died.
    * Wound, burns, amputation, chemical and biological agent exposure.
      * Mortality of 25%, many disabled or scarred for life.
    * Code of ethics developed in aftermath.
      - Informed consent.
      - Anticipated results should justify experiment.
      - Human experiments should be based upon animal results.
      - Physical and mental suffering and injury should be avoided.
      - There should be no expectation of death or disabling injury.
      - Degree of risk should be weighed by potential benefit.
      - Proper preparation & precautions should be taken.
      - Only qualified scientists should conduct medical research.
      - Subject has right to end experiment at any time.
      - Scientist must be prepared to end experiment if subject at risk.
    * Code did not have much effect.

=== Milgram obedience experiments ===

    * Designed to answer question "Could it be that Eichmann and hist milion accomplices in the Holocaust were just following orders?"
    * Subject was "teacher," learner was an actor paid by researcher, following a script.
    * Subject asked to administer electrical shocks when learner was wrong.
    * Psychologists said 1 in 1,000 would administer maximum shock (thus obeying supervisor).
    * In reality, 63.75% administered the maximum shock.
    * "I observed a mature and initially poised businessman enter the lab smiling and confident. Within 20 minutes he was reduced to a twitching, stuttering wreck, who was rapidly approaching a point of nervous collapse." S. Milgram in //Obedience to Authority//.

=== Belmont Report ===

== Basic Principles ==

  * Respect for persons.
  * Beneficence.
  * Justice.

== Institutional Review Board ==

  * IRB has authority to approve, require modification, or disapprove all research activities.
  * Purpose: Review research and determine if the rights and welfare of human participants involved in research are adequately protected.
  * Safeguard mechanism.

== Informed Consent ==

  * Informed consent is a process of information exchange that takes place between the prospective investigator, before, during, and after study.
  * Comprehension: Investigators responsible for ascertaining that the participant has comprehended the information.
  * Voluntariness: Agreement to participate in the research constitutes a valid consent only if voluntarily given.
    * Must not be coerced through any means, including incentive.

== Investigator's Responsibilities ==

  * Investigators bear ultimate ethical responsibility for their work with human participants.
  * Other responsibilities include:
    * Compliance with laws.
    * Assuming fiscal management.
    * Supervising/training of students, post docs, and residents.
    * Complying with terms and conditions of sponsor's award.
    * Submission of all technical, progress, invention, and financial reports on timely basis.

===== Project Description =====

  * Groups of 4-5
  * Four phases:
    * Proposal (2/7)
    * Prototype 1 (2/21)
    * Evaluation plan (2/28)
    * Final system & evaluation (3/16)

==== Proposal ====

Identify a real **usability** need, for a real population.

  * Describe the problem (current breakdown and the ideal situation).
  * Document the problem (how you know there is a problem to begin with).
  * Who are your users.
  * Ideas about a solution.

==== Prototypes ====

  * Build a presentation for a design gallery.

==== Evaluation Plan ====

Based upon feedback from prototype and problem you identified:

  * Write a convincing and realistic evaluation plan to see if you have reached all/some of your objectives.
  * Perform said evaluations on your fellow students.

==== Final Presentation ====

  * Just like prototype presentation, but you add in your final design, how it evolved, etc.

===== Other Study Techniques =====

==== Cognitive Walkthrough ====

  * Subject is usually an expert in UI, etc.
  * Think-Aloud protocol is part of cognitive walkthrough:
    * User describes verbally what he's thinking while performing tasks.
      * What they believe is happening.
      * Why they take an action.
      * What they are trying to do.
    * Researcher takes notes about task and actions.
    * Makes less assumptions about why things are happening.
  * Very widely used.
  * Yields good results with few people.
  * Potential problems:
    * Can be awkward for participant.
    * Can modify way user performs tasks.

=== Alternative ===

  * What if thinking aloud will be too disruptive?
  * Can use post-event protocol.
    * User performs session, then watches video and describes what she was thinking.
    * Sometimes difficult to recall.
    * Opens up door of interpretation/rationalization.

==== Related: Diary Study ====

  * Subject asked to keep journal of daily activities.
    * Record actions, reasons, and other observations.
  * Not always subjective.
  * Prevents researcher from having to be everywhere 24/7.

==== Interviews ====

  * 3 types:
    * Structured:
      * Well-defined agenda.
      * Efficient.
      * Require training.
    * Unstructured:
      * No agenda.
      * Let subject go in whatever direction they need to go.
      * Difficult to not influence direction.
      * Inefficient.
      * Less training.
    * Semi-structured:
      * Good balance of training/efficiency.
      * Often appropriate.

=== Semi-Structured Interviews ===

  * Predetermine data of interest - know why you are asking questions, don't waste time.
  * Guidelines:
    * Stay concrete (specific).
      * "So when the new guy joined the team and hadn't gotten his email account set up yet, what happened then?" vs. "What generally happens here when someone new joins the team?"
    * Signs to look for:
      * Interviewee waves hand and looks up at ceiling => generalization coming.
      * Use of passive voice, "generally", "usually", "should", "might"

==== Surveys ====

  * General Criteria
    * Make questions clear and specific.
    * Ask some closed questions with a range of answers.
      * Sometimes also have a no opinion option, or other answer option.
    * Do test run with two or three people.
  * Likert Scale
    * Usually odd # of points: 5, 7 point scale; agree to disagree.
    * Could also use words for each level.
    * Sometimes need to use black & white answer questions to get a normalization range.
  * Other Typical Questions
    * Rank importance of each of these items...
    * List the four most important tasks that you perform (open question).
    * List the pieces of information you need to have before making a decision about X, in order of importance.
    * Are there any other points you would like to make?

===== Participatory Design =====

  * Scandanavian history.
    * Scandanavia has fairly strong labor unions.
    * Workers involved in all decisions.
  * Emphasis on social and organizational aspects.
  * Based on study, model-building, and analysis of new and potential future systems.
  * User is a part of the team.
    * Immediate feedback.
    * Sanity checking.
    * Much tighter feedback cycle.

===== User Centered Design =====

==== Input & Output ====

  * Gather data:
    * Surveys/questionnaires.
    * Interviews.
    * Etc.

=== Represent Data ===

== Task Outline ==

  * List what task is about.
  * Add progressive layers of detail as you go.
  * Know in advance how much detail is enough.
  * Can add linked outlines for specific subtasks.
  * Good for sequential tasks.
  * Does not support parallel tasks well.
  * Does not support branching well.

== Use Cases/Scenarios ==

  * Describe tasks in sentences.
  * More effective for communicating general idea of task.
  * Scenarios: "informal narrative description"
    * Focus on tasks/activities, not system (technology) use.
  * Use Cases
    * Focus on user-system interaction, not tasks.
    * How to do a task using the system, not what tasks to do.

== Hierarchical Task Analysis ==

  * Graphical notation & decomposition of tasks.
  * Goals -- what the user wants to achieve.
  * Tasks -- do these to achieve the goals.
  * Looping, conditionals integrated.
  * See slides for example hierarchy.
  * Types of Plans:
    * Fixed sequence
    * Optional tasks
    * Waiting events
    * Cycles
    * Time-sharing
    * Discretionary

== ER Diagram ==

  * Objects/people with links to related objects.
    * Stress relationship between objects and actions.
  * Close to the type of thing you would say to a DB designer or programmer.
  * More difficult for user to understand.
  * No way to represent knowledge, ideas, motivation, etc.
  * Lends itself better in specifying to a developer what he needs to create.

== Flow Charts ==

  * Many types.
    * Decisions
    * Actions
    * Information flow
  * Combines ERD with sequential flow, branching, parallel tasks.
  * Tracks something being moved around.
  * Visually appealing, easy to understand.
  * More abstract than HTA.
  * Much quicker overview of system.

===== Midterm =====

  * What is usability engineering/HCI/user-centered design?
    * Define
    * Describe process/target problems
    * Arguments for UE/HCI/UCD/UE/HCI/UCD in historical context
  * Basics of human subjects research
    * Some history/background
    * Importance of Milgram experiments
    * Basics of Belmont report
  * Studying Users
    * Describe methods discussed in class
    * Argue pros & cons of each, different variations
    * Propose an approach to studying a given hypothetical place/situation, and argue why
    * How to organize and analyze data

===== Prototyping & Design =====

==== What is a prototype? ====

A prototype is a simplification of a system.

In interaction design, it could be:
  * Screet sketches
  * Storyboard
  * Slide show
  * Video simulation
  * Lump of wood (Physical mock up)
  * Software with limited functionality

==== Why prototype? ====

Put many ideas out there. By making prototypes, you can evaluate many options effectively.

Facilitates evaluation:

  * Stakeholders can see, hold, interact with.
  * Team members can communicate more effectively.
  * Test ideas yourself.
  * Encourages reflection.
  * Answer questions, support designers in choosing among alternatives.

==== What to prototype? ====

  * Work flow, task design
  * Screen layouts and information display
  * Difficult, controversial, critical areas

==== Compromises ====

All prototypes involve compromises. For software prototyping there may be a slow response, stetchy icons, limited functionality, etc.

==== Low Fidelity Prototyping ====

  * Rough prototype of system.
  * Uses medium unlike the final medium.
  * Quick, cheap, easily changed.
  * Encourages high level criticism; problems with conceptual models and fundamental usability or functionality issues.
  * Users unafraid to suggest major changes.

=== Storyboards ===

  * Often used with scenarios.
  * Indicate a series of events.

==== High Fidelity Prototyping ====

  * Looks and behaves like a subset of the final system.
  * Commanly used tools: Director, VisualBasic, Smalltalk
  * Users may think they have a full system (problem)
  * Get at details of design (layout, icons, colors)
  * Should not think of prototype as part of finished system (no recycling)

==== Medium Fidelity? ====

  * Somewhere in between.
  * High production values, no/limited interaction.
  * E.g. Photoshop
  * Tests detail of design without commiting.
  * Because no functionality, less pressure from users.

==== Prototyping & Evaluation ====

  * (Early)
  * (Low fidelity)
  * Rough out on paper
  * Cognitive walkthrough
  * Formative evaluation
  * (Late)

See slides.

===== Formative Evaluations =====

  * Done on low fidelity prototypes.
  * Wizard of Oz - smoke and mirrors to simulate working system.
  * GOMS and action analysis - uses models to predict certain attributes of prototypes.
  * Cognitive walkthroughs.
  * Heuristic evaluations - artificial evaluation using a top-ten list of mistakes or good practices.

===== Project 2 - Initial Prototypes =====

Prepare a prototype that answers two things:
  * What is the problem?
    * Who are users?
    * What are their needs?
    * What are constraints?
  * What is your solution?
    * Present multiple prototypes.
    * Sketches, storyboards, mockups.
    * Why for each. Pros/cons.

===== Human Stuff =====

==== Cognitive Processes ====

  * Attention
  * Perception and recognition
  * Memory
  * Learning
  * Reading, speaking, listening
  * Problem-solving, planning, reasoning, decision making

==== Senses ====

  * Sight, hearing, touch important for design of current interfaces.
  * Smell, taste?
  * Balance and propioception (where limbs etc. are physically)

=== Key Sense Concepts ===

  * Absolute threshold
    * Thresholds that determine what range you can sense.
    * Upper and lower thresholds.
  * Signal detection theory
    * Ability to tune in/out stimuli.
  * Just noticeable difference
    * How much change is required before you sense the difference?
  * Sensory adaptation
    * We react to change.
    * Absense of change leads us to loose sensitivity (psychological nystagmus).

=== Vision ===

  * Visual Angle
    * Total: 200 degrees.
    * High-res: ~15 degrees.
  * Rods
    * 120 million.
    * B&W
    * 1000x more sensitive than cones.
  * Cones
    * 6-7 million.
    * 64% red.
    * 32% green.
    * 2% blue.
  * Phenomena
    * Color perception:
      * 7-8% males cannot distinguish red from green.
      * 0.4% of women.
    * Peripheral vision is largely movement oriented.
    * Stereopsis:
      * (Stereopsis is ability to see in three dimensions.)
      * Monocular (size, interposition, perspective, paralax)
        * Ability to detect depth with one eye.
      * Binocular (retinal disparity, accommodation)
        * Ability to detect depth with two eyes.

=== Hearing ===

  * Capabilities
   * Frequency: 20-20,000 Hz
   * Loudness: 30 - 100 dB
   * Location: 5˚ source & stream separation
   * Timbre: Type of sound (lots of instruments)
  * Often take for granted how good it is.

=== Motor System ===

  * Our output system.
  * Capabilities
   * Range of movement, reach, speed, strength, dexterity, accuracy.
   * Workstation/device design.
  * Often cause of errors:
   * Wrong button.
   * Double-click vs. single.
 * Principles
   * Feedback is important.
   * Minimize eye movement.

==== The Model Human Processor ====

  * Classic study from CS perspective of how brain works
    * Microprocessor-human analogue using results from experimental psychology.
    * Provides a view of the human that fits much experimental data.
    * But it is partial model.
  * Focus is on a single user interacting with some entity (computer, environment, tool).

=== Memory ===

  * Perceptual "buffers":
    * Brief impressions
  * Short-term (working) memory:
    * Conscious thought, calculations.
    * Different store for visual vs. auditory memory.
    * Order of seconds.
  * Long-term memory:
    * Minutes, hours, days, years, decades.
    * Long term, large storage space.
    * Access is harder, slower.
    * Retrieval depends upon network of associations.
    * Memory Structure
      * Episodic Memory
        * Events and experiences in serial form.
        * Helps us recall what occured.
      * Semantic memory
        * Structured record of facts, concepts, skills.
        * One theory says it's like a network.
        * Another uses frames & scripts.

==== Decision Making Models ====

Understanding cognition important because it helps you understand how to teach people.

  * Production systems
    * If-then rules
    * Work like a computer program
  * Connectionism (big idea in AI)
    * Neural networks
    * Hidden Markov models
    * Bayesian networks
    * Modeled after a network of nodes
      * Nodes are factoids or rules.
      * Connections between.
      * Any time you follow a path that leads to success, strengthen the path.
      * Any time you make a mistake, weaken the path.
  * Mediated action
    * Actions must be interpreted in context
    * Tools, setting, culture affect
    * Objects "tell" us how to use it
    * The way things are shaped and presented affects how people interact with them
  * Case-based reasoning
    * Learn from experience, reasoning same as memory
    * Plans, schemes, and automation
    * Take closest matching experience and modify it to meet requirements
  * External/embodied cognition
    * Emphasizes reflexes and stuff

===== Evaluation =====

  * Evaluation is part of the design cycle.

==== Why evaluate? ====

  * If you make a mistake and don't catch it, it'll screw you later.
  * If we think of design as iterative process, we need to evaluate whether we're getting better.
  * Also, at each stage of design we make assumptions. We need to check whether those assumptions match reality.

==== What is evaluation? ====

  * Different from requirements gathering:
    * Testing a hypothesis.
    * Often use different methods, more focused.
  * Methods you choose depend on debates:
    * Quant. vs. quals.
    * Controlled vs. ecological validity
    * Cost vs. relevance.

==== Steps Involved ====

  * Formulate hypothesis.
    * Hypothesis = statement of fact.
    * Important to have hypothesis for data analysis.
  * Design a test plan.
    * Picking a method.
    * Selecting users.
    * Writing out procedure.
  * Get IRB permission.
  * Deal with users.
  * Deal with data.


==== Testing Methods ====

  * Formative
  * Artificial/Controlled
    * Isolate variables, level playing field.
    * Removes "noise" from data.
    * Thoroughly documented.
    * Focus **only** on your question.
  * Issues:
    * Putting people in contrived environment causes changes in how people interact.
    * Results from controlled experiments can't be directly compared to real world.

==== Hypothesis Testing ====

  * Example hypotheses:
    * X is better/larger/faster than Y.
    * X improved more than Y.

  - Specify null hypothesis (H0) and alternative hypothesis (H1).
    - Define H1 = true iff H0 = false.
  - Select significance level. Typically P = 0.05 or P = 0.10
  - Sample population and calculate statistics.
  - Calculate probability (p-value) of obtaining a sta...
(SEE SLIDES)

==== Dealing with Data ====

  * Academic honesty key.
    * Falsifiability of results.
    * Need for meticulous records.
      * Keep records unmodified.
    * Objectivity.
    * Peer review.
    * Replication.
      * Not done in software design.

==== Statistical Significance ====

  * Statistical significance means: Two populations differ to a significant extent along some variable.
  * Statistical significance does NOT mean noteworthy.
  * Typically in either rate of occurance, or the value of some result.
    * E.g. group A 2x likely to do well on tests than group B (statistically significant), yet the difference in scores may not be large enough to be significant.

==== Significance: Type I and II Errors ====

  * What does significance mean?
    * Type I: False negative.
    * Type II: False positive.
  * Set significance to balance risks of type I or II errors:
    * When might low type I and high type II (vice versa) be preferable?
  * These types of errors may arise from equipment limits, etc.

==== Predictive Models ====

  * Models used to predict human behavior, responses.
  * Stimulus-Response
    * Hick's law:
      * Decision time to choose among N equally likely alternatives.
      * T = Ic log2(n+1)
        * Ic = time to recognize each item = 150msec
      * Useful for pilot tests.
    * Fitt's law.
      * Time it takes to select something on screen.
      * ID = log2(d/w + 1.0)
        * d = distance; w = width of target; ID = index of difficulty
  * Cognitive - human as interpreter/predictor - based on Model Human Processor:
    * Keystroke Level Model:
      * Puts together lots of mini-models, comes up with larger coherent model.
      * Assigns times for basic human operations - experimentally verified.
      * Based upon MHP.
      * Accounts for:
        * Keystroking: Tk
        * Mouse button press: Tb
        * Pointing: Tp
        * Hand movement between kbd/mouse: Th
        * Drawing straight line segments: Td
        * "Mental preparation": Tm
        * System response time: Tr

==== Within-Subject or Between-Subject Design ====

  * Between subjects: Pool using prototype 1, separate pool using prototype 2.
    * Clean statistics -- less noise.
  * Within-subjects: Same subject uses both prototypes.
    * Removes people variations.

===== Heuristic Evaluation =====

==== Discount Usability Engineering ====

  * Cheap
    * No special labs/equipment.
    * More careful you are, the better it gets.
  * Fast
    * On order of 1 day to apply.
    * Standard usability testing may take a week.
  * Easy to use
    * Can be taught in 2-4 hours.
  * Reliance on discount UE can lead to sloppiness.
    * Easy to ignore more thorough evaluation methods.
    * Not all you need.

==== HE Overview ====

  * Developed by Jacob Nielsen.
    * Involves a set of guidelines -- heuristics.
    * Rules come from real-world experience.
  * Helps find usability problems in UI design.
  * Small set (3-5) of evaluators examine UI.
    * Independently check for compliance with usability principles (heuristics).
    * Different evaluators will find different problems.
    * Evaluators only communicate afterward; findings are then aggregated.
  * Can perform on working UI or sketches.
  * Most important ideas:
    * Independent analysis.
    * Performed on sketches or UI.

==== Process ====

  * Evaluators go through UI several times.
    * Inspect various dialogue elements.
    * Compare with list of principles.
    * Consider other principles/results that come to mind.
  * Usability principles:
    * Nielsen's "heuristics".
    * Supplementary list of category-specific heuristics.
      * May come from competitive analysis & user testing of existing products.
  * Fixes for violations may be suggested by heuristics.

==== Nielsen's Original 10 Heuristics ====

  * Simple & natural dialog
  * Speak user's language
  * Minimize user's memory load
  * Consistency
  * Feedback
  * Clearly marked exits
  * Shortcuts
  * Precise & constructive error messages
  * Prevent errors
  * Help and documentation

==== Heuristics -- Revised Set ====

=== Visibility of System Status ===

  * Keep user informed about what is going on.
  * Example: Pay attention to response time.
    * 0.1 sec: No special indicator needed.
    * 1.0 sec: User tends to lose track of data.
    * 10 sec: Max. duration if user to stay focused on action.
    * For longer delays, use progress bars.

=== Match between system and real world ===

  * Speak user's language.
  * Follow real world conventions.

=== Consistency & Standards ===

=== Aesthetic and minimalist desgin ===

  * No irrelevant info in dialogs.

==== HE vs. User Testing ====

  * HE much faster.
  * HE doesn't require interpreting user's actions.
  * User testing far more accurate.
    * Takes into account actual users and tasks.
    * HE may miss problems and find false positives.
  * Good to alternate between HE and user testing.
    * Find different problems.
    * Don't waste participants.

==== HE Results ====

  * Single evaluator achieves poor results.
    * Only finds 35% of usability problems.
  * 5 evaluators find ~75% of problems.
    * If they work as team, it's back down to 35%.
  * Why not more evaluators?
    * Adding evaluators costs more.
    * Many more evaluators won't find many more problems.

===== Evaluation (2) & Wrap-Up =====

==== Evaluation Pt. 2 ====

=== Usability Testing: The Usability Lab ===

  * A specially designed room for conducting controlled experiments observing a task.
  * Cameras, logging systems, people track what users do.
  * Good lab costs $$$.

== Observation Room ==

  * Three cameras capture subject, subject's monitor, and composite picture.
  * One-way mirror plus angled glass captures light and isolates sound between rooms.
  * Room for several observers.
  * Digital mixer for mixing of input images and recording to media.

== Other Capture - Software ==

  * Modify software to log user actions.
  * Can give time-stamped keypress/mouse events -- sync with video
  * Commercial software available ($$$)
  * Two problems:
    * Too low level, want higher level events
    * Massive amount of data; need analysis tools

== Complimentary Methods ==

  * Talkaloud protocols
  * Pre/post surveys
  * Participant screening/normalization
  * Compare results to existing benchmarks