User-Centred Requirements Handbook |
A successful system depends on the effective allocation of tasks between the system and the users. Different task allocation options may need to be considered before specifying a clear system boundary. A range of options are established to identify the optimal division of labour, to provide job satisfaction and efficient operation of the whole work process. The approach is most useful for systems which affect whole work processes rather than single user, single task products.
An important activity which integrates the system function identified with the organisational design (section 3.2) is the allocation of function. The objective of task allocation is to specify which functions should be carried out by the system and which by the users. This technique can also be used to identify elements of the user interface.
Task allocation decisions determine the extent to which a given job, task, function or responsibility is to be automated or assigned to a human. The decisions are based on many factors, such as relative capabilities and limitations of human versus technology in terms of reliability, speed, accuracy, strength, flexibility of response, cost and the importance of successful or timely accomplishment of tasks.
The goal of the design team is to allocate functions to the human, to the system and to the human-computer system in order to achieve effective, efficient and satisfying results. It is frequently a decision which designers make unconsciously rather than by deliberation, yet it establishes the framework within which relevant jobs and tasks will be done by users. Designers may be tempted to identify which functions the technology is capable of performing and then simply allocate the remaining functions to users, relying on their flexibility to make the system work. This does not make best use of users abilities and skills and can lead to unsatisfactory job design. Generally, it is better to involve users or their representatives in this decision and ensure that the resulting human functions form a meaningful set of tasks.
Benefits
• It counteracts the tendency to try and computerise the whole of a working system leaving users to carry out the remaining tasks regardless of the kinds of jobs this produces.
Limitations
• It requires some concept of the new system for users to contribute to the process and generate new options.
What you need
The analysts will need good understanding of existing job roles.
Process
To apply task allocation charts, the following steps are performed:
1. Each task or work process is identified.
2. Identify those for which there is some possibility of different task allocations.
2. For each task, a flow diagram is drawn up to show the existing split of tasks between users and computers, and the interactions between them.
3. Try to generate at least two charts (i.e. options for allocating tasks) to show task allocation between user(s) and computer for the new system.
4. Comment on the implications for job satisfaction and efficiency for each chart and annotate it accordingly.
5. Select the chart which is most acceptable to users, or generate new charts if necessary.
Practical guidelines
• Consider all the tasks and identify those for which there is some possibility of different task allocations.
• Try to develop more than one task allocation option to stimulate discussion within the design team or between users.
• Do not spend too long trying to produce neat diagrams. Rough drawings of possible allocations are adequate.
Reference
Ip, Damodaran, Olphert and Maguire (1990).
Form - Task allocation (Example)
| Task Allocation Chart (Example 1) | |||
| Task: Bank machine error report Version: 2 |
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| System: Bank machine | User: Member of staff | User: Engineer | System requirement |
State: Error warning displayed - If mechanical fault, send call automatically to engineer – If money or receipt paper has run out display signal. |
END Refill with money or receipt paper.END |
Receives signal. Rings bank to arrange visit to fix fault. |
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| Advantages: Immediate call to engineer. Speeds up process of fault reporting. |
Advantages: |
Advantages: |
Advantages: |
| Disadvantages: |
Disadvantages: No chance to investigate problem first. May feel controlled by engineer. |
Disadvantages: Feel controlled by machine. |
Disadvantages: |
| Task Allocation Chart (Example 2) | |||
| Task: Bank machine error report Version: 2 |
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| System: Bank machine | User: Member of staff | User: Engineer | System requirement |
| State: Error warning displayed |
Check if money or receipt paper running out. If so refill. END If engineering fault, call engineer. |
Respond to call. Agree time to visit. END |
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| Advantages: |
Advantages: Has control over the error process. |
Advantages: |
Advantages: |
| Disadvantages: |
Disadvantages: May not see signal quickly so service may be out of operation for some time |
Disadvantages: |
Disadvantages: |