Conceptual Models Conceptual model A conceptual model is

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Conceptual Models

Conceptual Models

Conceptual model • A conceptual model is: “a high-level description of how a system

Conceptual model • A conceptual model is: “a high-level description of how a system is organized and operates. ” (Johnson and Henderson, 2002, p. 26) • Need to first think about how the system will appear to users (i. e. how they will understand it)

From David Liddle • The most important thing to design is the conceptual model.

From David Liddle • The most important thing to design is the conceptual model. Everything else should be subordinated to making that model clear, obvious and substantial. That s almost the opposite of how most software is designed (Liddle, 1996, p. 17)

What is a conceptual model? • It is NOT a description of the user

What is a conceptual model? • It is NOT a description of the user interface • It is an abstraction (structure) that outline what people can do with a product and what concepts are needed to understand how to interact with it.

Why a conceptual model is needed? • Why not start with the nuts and

Why a conceptual model is needed? • Why not start with the nuts and bolts of design? – Architects and interior designers would not think about which colour curtains to have before deciding where the windows will be placed in a new building – Enables “designers to straighten out their thinking before they start laying out their widgets” (p. 28) – Provides a working strategy and a framework of general concepts and their interrelations

Conceptual models help the design team… • Orient themselves towards asking questions about how

Conceptual models help the design team… • Orient themselves towards asking questions about how the conceptual model will be understood by users • Not to become narrowly focused early on • Establish a set of common terms they all understand agree upon • Reduce the chance of misunderstandings and confusion arising later on

Main components of a conceptual model • Major metaphors and analogies that are used

Main components of a conceptual model • Major metaphors and analogies that are used to convey how to understand what a product is for and how to use it for an activity. • Concepts that users are exposed to through the product • The relationships between the concepts – e. g. , one object contains another • The mappings between the concepts and the user experience the product is designed to support

A classic conceptual model: the spreadsheet • Analogous to ledger sheet • Interactive and

A classic conceptual model: the spreadsheet • Analogous to ledger sheet • Interactive and computational • Easy to understand • Greatly extending what accountants and others could do www. bricklin. com/history/refcards. htm

Why was it so good? • It was simple, clear, and obvious to the

Why was it so good? • It was simple, clear, and obvious to the users how to use the application and what it could do • “it is just a tool to allow others to work out their ideas and reduce the tedium of repeating the same calculations. ” • capitalized on user’s familiarity with ledger sheets • Got the computer to perform a range of different calculations and recalculations in response to user input

Another classic • 8010 Star office system targeted at workers not interested in computing

Another classic • 8010 Star office system targeted at workers not interested in computing per se • Spent several person-years at beginning working out the conceptual model • Simplified the electronic world, making it seem more familiar, less alien, and easier to learn Johnson et al (1989)

The Star interface

The Star interface

ty i v i t c A Compare the conceptual models for Visicalc and

ty i v i t c A Compare the conceptual models for Visicalc and the star interface 1. What similarities do they share in their use of analogy and core concepts? 2. How do they differ? Text p 53

Summary points • A conceptual model is a high-level description of a product –

Summary points • A conceptual model is a high-level description of a product – what users can do with it and the concepts they need to understand how to interact with it • Decisions about conceptual design should be made before commencing any physical design • Interface metaphors are commonly used as part of a conceptual model