User-Centred Requirements Handbook |
The aim of this section is to develop one or more ideas upon which the new design would be based. Each idea may be regarded as a system concept.
It is desirable to develop several concepts and to compare them. The most feasible concept is then taken forward as part of the user requirements specification. It is also likely that the best parts of different concepts will be used to create as a single, agreed basis for the design.
Process
The following methods may be used to generate system concepts. These include:
• a brainstorm (section 4.1) session where design team members and users think and present ideas in an unconstrained manner.
• a parallel design (section 4.10) session where different groups, given the same design brief, come up with their own concept. Afterwards the different concepts are compared and the most feasible one is taken forward.
To allow users to visualise and assess a system concept, it may be represented as:
• a set of written scenarios (section 4.12) of how the new system might be used
• a storyboard (section 4.13) presenting a sequence of drawings showing the system in action
• a paper prototype (section 4.9) which users may manipulate
Descriptions and guidance on applying all the above techniques are given in
Part C (section 4) of this document.
A list of the suggested ideas and concepts should be produced as an index. Form 1.10 provides an example list:
Form 1.10 - Design Ideas and Concepts
(Example showing form partially completed)
| 1.10 Design ideas and concepts | |||
System:New bank machine |
|||
| Ideas and Concepts | Comments |
Take Forward? /Ref. |
|
| General ideas | |||
| Speech synthesis for guidance. | |||
| Goal specific | |||
|
G1 Access required service quickly and safely |
Question and Answer mode for beginners. | ||
|
G2 Replenish money |
Simple reload drawer while machine still running. | ||
|
G3 Replenish paper |
Simple reload drawer while machine still running. | ||
|
G4 Report fault with bank machine |
Allow user user to notify bank if their card gets stuck in the machine, by pressing special button. | ||
|
G5 Repair fault |
Allow bank staff to repair some faults to save visit from maintenance staff. | ||
Transfer those taken forward to
Form 3.5 Functions and Features
Designing user interfaces is a complex and highly creative process that blends intuition, experience, and careful consideration of numerous technical issues. Designers should begin with a thorough task analysis for the user community. Explicit recording of task objects and actions based on task analysis can lead to the useful construction of metaphors or system images. There are several methods for envisioning design as described in Chapter 22 of Preece et al (1994). These include the use of sketching, scenarios and storyboards.
Once the general design concept is produced, the computer objects that users need to perform their tasks and the actions they will perform with them will be identified. Next designers create consistent and meaningful syntactic forms for input and display. Extensive testing and iterative refinement are then performed early on to validate the design.
There are several methods for representing the logical structure of a user interface during the design process such as flow charts, dataflow diagrams, state transition diagrams, and structure charts (see Hartson and Hix, 1989, Hartson et al, 1990, and Sutcliffe, 1991). Selection of an appropriate user interface style or combination of styles is also an important part of user interface design. The style must be appropriate for the users, the work they are doing, the system and the environment. Preece (1994), chapter 13 offers an up-to-date and useful general overview of the different interaction styles. Shneiderman (1987) discusses in depth menu dialogues, command languages, and was one of the first to offer practical guidelines on the design of direct manipulation interfaces.
User-interface structures, for particular user goals or task steps, may also be developed to illustrate the ideas listed in Form 1.10 (as shown below). Figure 5 (Example 1) shows a global interface structure for bank machine access (goal 1), while Figure 6 (Example 2) expands on the tasks of inserting a card and entering a PIN.
User interface design (Example 1)
User goal: G1 Access required service quickly and safely
Figure 5. Global user-interface structure
User interface design (Example 2)
User goal: G1/T2 and T3 - Inserting card and entering a PIN
Figure 6. Expansion of user-interface component
The proposed organisational design can be expressed with a diagram, using simple symbols, as shown below in the Figure below:
Figure 7. Organisational process diagram
The organisational design should be supplemented with a written description to explain the process.
It is possible to simulate the organisational design by setting up a working environment, such as a simulated office with people acting out different user roles. Such simulations can then can then be assessed either:
• by performing an expert review (section 1.11) to walk through the system concept without an operational system in place, or
• by testing with a prototype system (section 2.6).