Understanding Task Analysis

1. Understanding Task Analysis NIK ISROZAIDI NIK ISMAIL

2. Learning outcomes • At the end of this lecture, you should be able to: • Draft the Hierarchical Task Analysis (chart or textual based)

3. Key terms • Task analysis • Hierarchical task analysis

4. Task Analysis - What’s a Task? • A set of human actions that contributes to a functional objective and to the goal of the system. • Scope or size of a task is determined by the definition of the objectives. • Each task should be approximately equal in size. • But not always the case

5. Task - Decomposition

6. Task - Decomposition • Goal - state of the system that a human wants to accomplish. • Task - activities required, used, or deemed necessary to achieve a goal. • Actions - steps required to complete the task.

7. Task Analysis • A method/set of methods for understanding the tasks users carry out with a product/system • To analyze the underlying rationale and purpose of what people are doing; what are they trying to achieve, why are they trying to achieve it, and how are they going about it? • To investigate an existing situation • Can be used for many different purposes within design and evaluation activities

9. Task Analysis • Key definitions (Norman, 1988): • Goal - the state that the human wishes to achieve • Task - the activity required in order to bring about the state the human wishes to achieve (the goal)

10. Task Analysis • Task analysis techniques support user-centred design • Informs us (in detail) as to: • how users use existing products • how users may interact with future products • Can be used to: • improve current design • identify potential problems with new design • identify requirements for new design • design training materials and manuals • develop evaluation plans

12. Hierarchical Task Analysis • HTA is a commonly used means of breaking tasks down into a hierarchy of goals, operations (actions) and plans • It involves breaking a task down into subtasks and then into sub – subtasks • These are then grouped together as plans that specify how the tasks might be performed in an actual situation

13. Procedure for carrying out HTA • The starting point is a user goal, then examined the main tasks associated with achieving that goal. Where appropriate, these tasks are subdivided into subtasks • Start with the overall goal (verb-noun pair), e.g. “Use email”, “Print a letter” • Break these down into meaningful sub goals/tasks (asking how question) • Break down sub goals further until reach an appropriate stopping point

14. Procedure for carrying out HTA • Add plans to the analysis - conditional statements, often utilizing Boolean logic, e.g. • DO 1, THEN 2, THEN (IF condition = true) DO 3, ELSE DO 4, THEN EXIT • Represent the goals, sub goals, operations and plans using either: • graphical views (boxes and arrows) • non-graphical methods (e.g. tabulation, outlines, textual)

15. HTA Structure Chart Notation

16. Stages of a HTA • Starting the analysis • Specify the main task. • Break down main task into 4-8 subtask, and specify in terms of objectives. Cover the whole area of interest • Draw out as layered plans, logically & technically correct. None should be missing.

17. Stages of a HTA • Progressing the analysis • Decide on level of detail and stop decomposition. Should be consistent between tasks. Can range from detailed to high level description. • Decide if a depth first or breadth first decomposition should be done. Can alternate between the two. • Label and number the HTA.

18. Stages of a HTA • Finalizing the analysis. • Check that decomposition and numbering is consistent. May produce a written account of the processes. • Have a second person look it over. They should know the tasks but not be involved in the analysis.

19. HTA – Graphical view

20. HTA – Graphical view

21. HTA – Textual representation • HTA can also be written as a list like this: 0. to clean house 1. get vacuum cleaner 2. clean rooms 2.1 clean hall 2.2 clean living rooms 2.3 clean bedrooms etc 3. empty dust bag 4. put vacuum cleaner away Plan 0: do 1,2,4 when dust bag full, do 3 Plan 2: do any of 2.1, 2.2, 2.3 in any order depending on which rooms need cleaning.

22. An example of HTA for a Microwave Oven • What is the overall goal? • “Cook food!” • How is this done? • Prepare meal • Put meal in oven • Select programme • Listen for bell to ring • Remove meal

23. An example of HTA for a Microwave Oven • Selecting a programme - How is this done? • Set to auto sensor • Set to defrost • Set timer to cook • What are the rules that influence the order in which tasks/subtasks take place? (the plans)

24. An example of HTA for a Microwave Oven

25. Further Task Analysis (Matrixes)

26. Task Analysis – Critical thinking • Some requirements that might have ‘emerged’ from carrying out this Task Analysis: • The need for a distinctive, but not annoying, bell sound • The need for an easily accessible mechanism for opening the door • The need for a highly learnable (guessable) means of selecting a programmed

27. Assumptions about the interface • Must be made to fulfill the system requirements. • Very true if we are describing how users behave on an existing system. • Should not be made when we are designing a new system. • Don’t limit our options before we start.

28. Q &A