Iteration and prototyping hole topic.

1. iteration and prototyping
getting better …
… and starting well

2. prototyping
 you never get it right first time
 if at first you don’t succeed …
prototype evaluatedesign
re-design
done!
OK?

3. Prototyping JTB October 2004 3
Overview
 Prototyping is a well understood and used
technique in engineering where novel
products are tested by testing a model
prototype
 prototypes can be “throw away” (e.g., scale
models) or go into commercial use (Concorde!)
 In software development prototypes can be
 paper-based -
 software-based

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What is Prototyping?
 Essential element in user centred design
 Is an experimental and partial design
 Involves users in testing design ideas
 Typically done very early in the design process
 Can be used throughout the SDLC
 Different types of prototyping are appropriate for
different stages of design
 Product conceptualization – requirements – task
match user acceptance

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What is a prototype?
In interaction design it can be (among other things):
a series of screen sketches
a storyboard, i.e. a cartoon-like series of scenes
a Powerpoint slide show
a video simulating the use of a system
a lump of wood (e.g. PalmPilot)
a cardboard mock-up
a piece of software with limited functionality
written in the target language or in another
language

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Why Prototype?
 Traditional software development: you can’t test until
you implement
 Implementation is expensive, and there is nothing to
test until you have made that expenditure of effort
and schedule time
 Result: any design errors are built in to the first thing
you can test, and it is very expensive to make
changes
 Result: design errors, unless they are really bad, are
left in the product

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Breaking this implementation
paradox
 Build a prototype of the basic functionality,
especially the interface
 Test the prototype, which will uncover design
errors
 Correct the errors
 Repeat until you have a clean design
 A major tool for improving usability
 Heavily used in industry

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What to prototype?
•Work flow, task design
•Screen layouts and information
display
•Difficult, controversial, critical areas

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Low-fidelity Prototyping
•Uses a medium which is unlike the final medium,
e.g. paper, cardboard
•Is quick, cheap and easily changed
•Examples:
sketches of screens, task sequences, etc
‘Post-it’ notes
storyboards
‘Wizard-of-Oz’

10. 10
Prototyping Techniques
 Paper Prototyping
 Build it
 Wizard of Oz
 None are perfect -- research lies in
creating tools & techniques that will
support rapid development and
evaluation

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Paper Prototyping
 Sketch it out on paper
 Fast, simple, effective
 Simulate “computer”, get feedback about real use
 Problems
 Only really effective in well-constrained environments
 Limited to desktop-like applications

12. 12
Build it
 “sketch” it out on a computer
 Existing prototyping tools & UI builders
 Easy to create familiar look and feel
 Problems
 Existing tools limited to the desktop
 Lack support for small, mobile devices
 Lack support for variety of input and output
 Familiar look and feel limited to our culture

13. 13
Wizard of Oz
 Fake it
 Only “prototype” the surface
 Use a human “behind the curtain” to fake the rest
 Particularly good for recognition
 Problems
 Easiest to do in a constrained environment
 How does one “fake” rapid sensor input, etc?
 Wizard must understand dialect, culture, etc.

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Paper Based Prototyping
 Paper based prototypes
 These have no functionality but can still be useful
for:-
 Generating ideas
 Gaining insights into what the user might want or is thinking
Eg a paper based design of a data entry screen
 Storyboards and Snapshots
 using “film-scripting” techniques to visualise
interactions between users and the system
 This is very quick and cheap

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Storyboards
•Often used with scenarios, bringing more
detail, and a chance to role play
•It is a series of sketches showing how a
user might progress through a task using
the device
•Used early in design

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Sketching
•Sketching is important to low-fidelity
prototyping
•Don’t be inhibited about drawing ability.
Practice simple symbols

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•Index cards (3 X 5 inches)
•Each card represents one screen
•Often used in website development
Using index
cards

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Elements of a paper prototypeMenu Bar
Scroll
Bar
Secondary
Menu
Opening
Contents

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The home page
Pulldown
menu

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A second-level page

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Another second-level page

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After prototyping and user testing,
this is what their home page looked
like

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High-fidelity prototyping
•Uses materials that you would expect to be in
the final product.
•Prototype looks more like the final system than
a low-fidelity version.
•For a high-fidelity software prototype common
environments include Macromedia Director, Visual
Basic, and Smalltalk.
•Danger that users think they have a full
system…….see compromises

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Aims of Prototyping in
Software
The aim of prototyping is to resolve
uncertainty about
 functional and user requirements
 operation sequences
 user support needs
 required representations
 “Look and Feel” of the interface
 appropriateness of the design

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Software Prototyping
 A software prototype will be a version of the
proposed system with limited functionality
 Will differ from the final system in terms of
 Size, reliability robustness & completeness
A software prototype
 is “executable”
 can be thrown away, or evolve
 may serve many different purposes
 should be “quick and dirty” (and cheap!)
 is an integral part of user-centred design approaches
based on evaluation/modification

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Prototyping Techniques
The three major kinds of prototyping are
 “Throw away” prototyping (a.k.a. “rapid
prototyping”)
 used exclusively in requirements gathering
 Incremental prototyping
 not actually prototyping at all, but the delivery of
prioritised functions incrementally to a single, overall
design
 Evolutionary prototyping (a.k.a “Rapid Application
Development, RAD)
 as for incremental prototyping but with evolving design

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Rapid Prototyping
 Aims to collect information on
requirements and the adequacy of
possible designs
 Recognises that requirements are likely
to be inaccurate when first specified
 The emphasis is on evaluating the
design before discarding it

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Incremental Prototyping
 Final product is built as separate components one at
a time
 There is one overall design for the system
 It is partitioned into independent and smaller
components
 Final product is released as a series of products
 Eg General student details data module – the students
assessment profile module

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Evolutionary prototyping – RAD
 As for incremental prototyping
 Additions and amendments are made following
evaluation and the system is regenerated in its
amended form
 In this case the prototype evolves into the final
system

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Other Prototyping Techniques
 Full prototype
 full functionality, lower performance than production software
 Horizontal prototype
 displays “breadth” of functionality, no lower level detail “back end”
support Eg. Database link
 Vertical prototype
 full functionality and performance of a “slice” or small part of the
system
• Two common types of compromise
• ‘horizontal’: provide a wide range of functions, but
with little detail
• ‘vertical’: provide a lot of detail for only a few
functions