1. Prototyping Hix & Hartson:
Developing User Interfaces: Ensuring Usability Through Product & Process
Deborah Hix and H. Rex Hartson
© 1993 John Wiley & Sons, Inc.
ISBN
See also:
Low vs. high-fidelity prototyping debate
James Rudd, Ken Stern, and Scott Isensee
Interactions v.III n.1 (Jan. 1996) pp.76-85
<URL:
Prototyping for usability of new technology
Roger R. Hall
International Journal of Human-Computer Studies v.55 n.4 (Oct 2001) pp
<URL:

2. Readings in Preece et al.
Chapter 27 (prototyping)
Chapter 28 (software support)

3. Introduction
Many in the software industry have discovered that building the system the user really wants and needs is tricky
Often users are not sure of exactly what functions they would like the system to perform
Many times users have difficulty communicating their needs to the system developers
In addition, users may have faulty expectations regarding automation
Users may be unaware of some of the power, flexibility and features computer systems can offer
They may overestimate the functionality they can obtain for their projected investment

4. Rapid Prototyping Is…
Rapid prototyping facilitates the development of software projects and especially UIs

5. Traditional Non-prototyped Approach
In the traditional ‘waterfall model’ of software engineering, each phase of the software development cycle occurs in linear, non-iterative order

6. Prototyping Approach
Rapid prototyping is a technique which directly addresses these user problems
A prototype is a model not a refined and finished product
GUI builders can be used as prototyping tools

7. Steps
Prototyping in general can be described as having a series of steps (Scharer, 1983):
Preliminary fact-finding
Pre-generation design stage
Prototype generation
Prototype refinement
Wouldn’t it be great to have the sources down here in the notes?
Preliminary fact finding  early analysis activities
Pre-generation design  design document
Prototype generation  developing the prototype & testing it
Prototype refinement updating protype based on testing results

8. How Does Prototyping Fit?
During the prototyping process the developer must decide whether to build a full prototype of the target system or only a portion of the system
Global vs. Local prototype, etc. (H&H §9.2.3)
Developers must also decide whether the prototype will be incorporated into the final system or if it is to be a ‘throw-away’ effort
Additionally, developers must schedule and integrate prototyping into the development cycle
H+H: Hix and Hartson (1993) Developing User Interfaces: Ensuring Usability Through Product & Process.

9. Advantages
Developers only truly understand the system requirements when they can see some form of implementation in action
Can lead to improved functional requirements, improved interaction requirements, and easier evolution of requirements
Experiments show improvements in products and communication

10. More Potential Advantages
The user interface is carefully designed and tailored to the users' needs
The user becomes involved more completely in the evolution of the product
The low cost and ready availability of at least some prototyping tools make their acquisition feasible even on a low budget and less productive

11. Approaches May be distinguished by detail and goals of prototype:
Scenario/storyboard
Demonstration
Version 0
Scenario/storyboard.
1. The user is presented an example on paper or on a computer of actual system usage.
2. However, the system only simulates the processing of fixed user data or queries.
3. Each frame of the storyboard or scenario represents one page or screen the user might see output from the system.
Demonstration. In this approach to prototyping, users are allowed to enter their own restricted set of data or to perform some limited set of functions.
1. The system typically processes some limited range of user queries or data, using limited files.
2. The usefulness of this type of prototype is greater than the scenario/storyboard approach because some true system functionality is exhibited, giving the user and the designer a better picture of the proposed system.
Version 0. In Version 0 prototyping the prototype is a working release of the system and is intended to be used under conditions similar to the final, targeted environment.

12. Version 0 Version 0 Advantages The main disadvantage
A working release of the system
Lacks full functionality
Advantages
Evolves into the final product
User sees progress being made on the product
The main disadvantage
Reluctant to throw out a bad design
Version 0. In Version 0 prototyping the prototype is a working release of the system and is intended to be used under conditions similar to the final, targeted environment.
1. The Version 0 prototype lacks full functionality, may be missing functions such as help and error messaging, and is expected to be altered through suggestions from the user.
3. Clearly, it is a goal of the Version 0 approach to create code which will be evolved into the released version of the system.
4. One advantage of this approach is that the prototype evolves into the final product, eliminating most throw-away code.
5. Another advantage is that the user sees progress being made on the product.
6. The main disadvantage is that the producers of the prototype may be reluctant to throw out a bad design or to incorporate important refinements which significantly alter the prototype.

13. Tools for Storyboard Prototypes
Pencil & paper
Drawing software
Screen shots from visual developers
To create storyboard prototypes, drawing software such as MacDraw, MacPaint, or Corel Draw can be used in place of paper and pencil to produce screen or report mock-ups.
1. The advantages of using these tools are the ease of modification, the ability to reproduce portions of each page and the neatness of the product.
2. The disadvantages are that the screen size, page size, and other characteristics of the target system must be known and taken account of in creating each storyboard frame.

14. Tools for Demonstration Prototypes
Programming languages
E.g. Visual Basic
Hypermedia
Hypercard-like systems
GUI WWW browsers

15. Tools for Version 0 (1)
Specific prototyping software
E.g. Marksman

16. Tools for Version 0 — UIMS
User interface management systems
Originally conceived of as tools to allow the user to customize the interface of a software package while maintaining the functionality
The tool facilitates the structuring of the screen, the handling of the dialogue between the human and the computer, and the sequencing of events

17. UIMS (2)
Advantages
Code that is created is separate from the functional parts of the system
Enforce style consistency among the user interfaces created using that particular UIMS
Evolving towards graphical programming languages
Disadvantages
High cost, limited availability and special hardware

18. Tools for Version 0 GUI builders and 4GLs
spreadsheet packages and database packages may have screen generators
Visual Basic
RapidApp
Tcl/Tk
Fourth Generation Languages. By adding overlays and using macros, spreadsheet packages can be used to create prototypes.
a. Database packages such as dBase IV and FoxBase include features which allow the designer to create screens and reports using high-level commands. Also Visual Basic.
b. The prototypes made with these sorts of system can readily become Version 0 systems.

19. Testing & Evaluation In Preece et al.: Review Read
Chapter 19 (requirements gathering)
Read
Chapter 29 (evaluation)
Chapter 30 (usage data)
Chapter 33 (predictive evaluation)