32
Scenario-Based Usability Engineering Chris North CS 3724: HCI

Scenario-Based Usability Engineering Chris North CS 3724: HCI

Embed Size (px)

Citation preview

Page 1: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Scenario-Based Usability Engineering

Chris North

CS 3724: HCI

Page 2: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Outline

• Scenario-based usability engineering:• Engineering• Usability

– Metrics– Tradeoffs

• Scenario-based– Scenarios– Claims analysis

• HCI background:• History• @ VT

• Class stuff:• HoF/S presentations• HW 1• Project

Page 3: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Engineering

• What is “engineering”?

• What is “science”?

• Myth: The user interface is tacked on at the end of the project

• Why don’t Waterfall models work?

Page 4: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Palm vs. Newton

Page 5: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Usability

• Usability = ???

• Metrics: What is measurable about usability?

• How do we know if system A is ‘better than’ system B?

Page 6: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Usability Metrics

• Ease of learning•

• Ease of use•

• User satisfaction•

“user friendly”

Page 7: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Usability Tradeoffs

• Can we simultaneously optimize all usability metrics?

• What factors impact tradeoff decisions?

• In usability engineering:• Identify tradeoffs

• Choose based on design goals

• Track tradeoffs for design rationale

Page 8: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Paper Pad vs. MS Word

+

-

+

-

Page 9: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Scenarios

Marissa was not satisfied with her class today on gravitation and planetary motion. She is not certain whether smaller planets always move faster or how a larger or denser sun would alter the possibilities for solar systems.

She stays after class to speak with her teacher, Mr. Boring, but she isn’t able to pose these questions clearly yet, so Mr. Boring suggests that she re-read the text and promises more discussion tomorrow.

Stories about people and their needs and activities

A problem scenario describes a current situation:

Page 10: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Marissa, a 10th-grade physics student, is studying gravity and its role in planetary motion. She goes to the virtual science lab and navigates to the gravity room.

In the gravity room, she discovers two other students, Randy and David, already working with the Alternate Reality Kit, which allows students to alter various physical parameters (such as the universal gravitational constant) and then observe effects in a simulation world.

The three students, each of whom is from a different school in the county, discuss possible experiments by typing messages from their respective personal computers. Together they build and analyze several solar systems, eventually focusing on the question of how comets can disrupt otherwise stable systems.

They capture data from their experiments and display it with several visualization tools, then write a brief report and send it for comments to her teacher Mr. Wright, who uses it for class discussion the next day.

A design scenario describes an initial vision:

What makes a good scenario?

Page 11: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Scenario Elements

• Setting• Actors (people, users)• Task goals (what I want to achieve)• Plans (how I will accomplish it)• Actions (do it)• Events (system response)• Evaluation (is that what I wanted?)

What are the advantages of scenarios?

Page 12: Scenario-Based Usability Engineering Chris North CS 3724: HCI

*Claims Analysis (see pgs 73-74)

Collaboration of multiple students

(high-level design)

+ students can learn from each other

+ encouragement

- competition for control

- distraction

Drag-and-drop planets into solar system

(detailed design)

+ easy to learn for short term usage

+ fun game-like, keeps students interested

- difficult to get precise placement

- difficult for repeatable experiments

1. Identify an important design feature (cause)2. Identify the advantages and disadvantages of that feature (effects)

How do you know?

Page 13: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Design

• Maximize the +’s

• Minimize the –’s

Collaboration of multiple students

+ students can learn from each other

+ encouragement

- competition for control

- distraction

Private simulation space?

?

Page 14: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Iterative Design

• Sometimes design is refinement

Page 15: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Iterative Design

• Sometimes design is radically transformational

Page 16: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Problem scenarios

summativeevaluation

Information scenarios

claims about current practice

analysis ofstakeholders,field studies

Usability specifications

Activityscenarios

Interaction scenarios

iterativeanalysis ofusability claims andre-design

metaphors,informationtechnology,HCI theory,guidelines

formativeevaluation

DESIGN

ANALYZE

PROTOTYPE & EVALUATE

Page 17: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Some History of HCI

Page 18: Scenario-Based Usability Engineering Chris North CS 3724: HCI

The Changing Face of Computer Use

1960’s

1970’s

1980’s

1990’s

2000+

Professional programmers,“software psychology”

Business professionals,mainframes, command-line

Large, diverse user groups,“the computer for the rest of us”

World Wide Web and more,information access & overload

Ubiquitous computing,diversity in task, device, …

Page 19: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Some History of HCI

• Vannevar Bush, 1945 “As We May Think”

• Vision of post-war activities, Memex

• “…when one of these items is in view, the other can be instantly recalled merely by tapping a button”

Page 20: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Some History of HCI

• Douglas Engelbart, 1962 “Augmenting Human Intellect: A Conceptual Framework”

• In 1968, workstation with a mouse, links across documents, chorded keyboard

Page 21: Scenario-Based Usability Engineering Chris North CS 3724: HCI

• XEROX (PARC) Alto and Star– Windows– Menus– Scrollbars– Pointing– Consistency– OOP– Networked

Some History of HCI

• Apple LISA and Mac– Inexpensive

– High-quality graphics

– 3rd party applications

Page 22: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Future of HCI

• Large displays• Small displays• Peripheral displays• Alternative I/O• Ubiquitous computing• Virtual environments• Augmented Reality

• Speech recognition• Multimedia• Media space• Artificial intelligence• Software agents• Games• ...

Page 23: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Center for HCI @ VT

• Doug Bowman• Dan Dunlap• Roger Ehrich• Steve Harrison• Rex Hartson• Deborah Hix• Andrea Kavanaugh• Brian Kleiner• Scott McCrickard• Chris North• Manuel Perez

• Francis Quek• Tonya Smith-Jackson• Deborah Tatar• Woodrow Winchester

Page 24: Scenario-Based Usability Engineering Chris North CS 3724: HCI

VT GigaPixel Display

Page 25: Scenario-Based Usability Engineering Chris North CS 3724: HCI

VTURCS

• VT UGrad Research in CS

• http://vturcs.cs.vt.edu

• Andrew Sabri:• High-Res Gaming:

WarCraft

• Conference presentation, journal paper

• Now at Electronic Arts

Page 26: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Presentations(Hall of Fame/Shame)

• See course calendar on website • Individual• 5% of grade• 5 minutes, 3-4 slides

• Practice

• Bring on CD, usb key, or laptop

• Pick UI of your choice (software or real-world)• UI critique

• Scenarios/tasks

• Claims analysis (include pictures)

• Redesign ideas?

• Vote: UI Hall of Fame/Shame

Page 27: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Fast Food Drive-Thru Menus

• Scenarios:• College students

• Hungry

• Get food, get out. FAST!

• Often: sandwich, fries, drink

• Typically: Not sure what I want

• Sometimes: Know what I want

• Passengers want food too

• Budget is important

Page 28: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Claims 1

• Billboard menu:• + all in one view enables fast recognition & decisions

• + organized by categories for quick learn

• + tabular layout, fast for visual scan of prices

• - see menu too late

• - passengers can’t see menu

Page 29: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Claims 2

• Microphone/Speaker Voice UI• + easy access

• + human in the loop, error recovery

• - passengers must order thru driver: slow, errors

• - winter, Brrrrr!

• - poor feedback: I can’t understand a word they say

• - they can’t hear me over my ’87 VW

Page 30: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Other good design features

• Combo meals (high frequency task = fast)

• Budget menu (Wendy’s)

• Get price before proceeding

• Some: visual feedback on order

• Small re-design ideas:• More menus back in line

• Menu on both sides of car

• Microphone on both sides

• Radical: cell phone, in-car UI

Page 31: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Homework #1

• Qualitative discussion• Usability problems, errors, access, alternate tasks, …

• Quantitative discussion• Data averages, min, max

• Data visualization

• Statistics, t-tests, …

Page 32: Scenario-Based Usability Engineering Chris North CS 3724: HCI

Projects