Task Analysis

1. Task Analysis Department of Biomedical, Industrial Engineering & Human Factors Engineering

2. What is Task Analysis? The study of what an operator (or team of operators) is required to do, in terms of actions and/or cognitive processes, to achieve a system goal. It provides the user with a “blueprint” of human involvement in a system. Reference: Kirwan, B. and Ainsworth, L.K. (1992. A Guide to Task Analysis Bristol, PA: Taylor & Francis Inc. Department of Biomedical, Human Factors, & Industrial Engineering

3. Why Conduct Task Analyses? • Ensure system safety through hazard identification, effective system design, human reliability assessment, and incident investigation • Enhance productivity through determination of where to automate system processes, evaluation of staffing and training requirements, and identification of error potential • Increase system availability by identification of maintenance demands, and requirements for maintenance support tools Department of Biomedical, Human Factors, & Industrial Engineering

4. When Is Task Analysis Done? • In System Design Throughout the life-cycle or the system: from initial concept development, through design, to construction, commissioning, and operation (also in system decommissioning) • In System Evaluation To assess impact when system changes, or as part of periodic reviews (audits or risk assessments) Department of Biomedical, Human Factors, & Industrial Engineering

5. Task Analysis Application Areas • Allocation of function Allocating functions between personnel and machines, and defining extent of operator involvement in the control of the system • Person specification Defining characteristics and capability requirements of personnel to enable to efficiently carry out the task Department of Biomedical, Human Factors, & Industrial Engineering

6. Task Analysis Application Areas cont. • Staffing and job organization Defining the number of staff required, the organization of team members, communications requirements, and allocation of responsibility • Task and interface design Ensuring adequate availability and design of information displays, controls, and tools to enable the operator(s) to adequately carry out the task Department of Biomedical, Human Factors, & Industrial Engineering

7. Task Analysis Application Areas cont. • Skills and knowledge acquisition Training and procedures design • Performance assurance Assessment of performance predicatively via human reliability assessment, retrospectively via incident investigation or analysis, or concurrently via problem investigations Department of Biomedical, Human Factors, & Industrial Engineering

8. Task Analysis and System Life-Cycle From Kirwan and Ainsworth, 1992 Department of Biomedical, Human Factors, & Industrial Engineering

9. Task Analysis Techniques - Overview Department of Biomedical, Human Factors, & Industrial Engineering

10. Analysis Procedures • Mission Analysis Function Determination • Function Allocation • Task Description / Identification • Task Analysis Department of Biomedical, Human Factors, & Industrial Engineering

11. Mission Analysis (System Requirements Analysis) • What is the system supposed to accomplish? • The analyst/designer needs to know - • Specific Goals • Required Outputs • Required Inputs • System Capacities and Performance Requirements • Operating Environmental Factors • Constraints on System Operation Department of Biomedical, Human Factors, & Industrial Engineering

12. Mission Analysis Tools • Mission Profile • Graphic Description (Example - Flight Profile) • Mission Scenario • Verbal Description - Summarizes typical assumptions, environments, operations. • Mission Segment • Time period of coherent activities with definite beginning and ending points. Department of Biomedical, Human Factors, & Industrial Engineering

13. Importance of Function & Task Analyses Evaluate Human Factors Implications Design Requirements and Constraints Workload Implications • Notes: 1. Decompose to level where functions to be performed by system can be identified. 2. Be careful that proposed design solution does not appear to be a function description. Department of Biomedical, Human Factors, & Industrial Engineering

14. Determination of Functions Identify and Describe Functions - by Determining Function Inputs and Outputs Establishing Functional Performance Criteria Preparing Functional Flow Diagrams Function Examples: To Detect To Repair To Analyze Department of Biomedical, Human Factors, & Industrial Engineering

15. Determination of Functions Functions - Can be Instantaneous (Start Engine) Prolonged ( Monitor Radar Screen) Complex (Analyze Equipment Malfunction) Department of Biomedical, Human Factors, & Industrial Engineering

16. Function Performance Criteria • Yardstick used to measure/predict whether or not the system/function meets the performance requirements. • Criteria can range from gross to finely detailed. • Functional Performance Criteria must be stated in terms of those test results that must be satisfied in order for the system/function to meet the performance requirements. • Provides the basis for preparing the Functional Flow Diagram. Department of Biomedical, Human Factors, & Industrial Engineering

17. Functional Flow Diagram • Determine the functions that have already been allocated. • Describe the various different ways that each unallocated function might be accomplished. • Establish the weighting criteria for comparing the alternatives. • Compare each of the alternative against one another. • Select the most cost-effective design. Department of Biomedical, Human Factors, & Industrial Engineering

18. Task Description / Identification • Examine each selected design alternative. • List in sequence all the actions that must be performed to accomplish the functional element. • Categorize actions in terms of whether they areoperator or maintainer activities; and by thehardware/software subsystems to which they belong. • Describe each action in terms of a behavioral verb (see next slide). • Break tasks down into subordinate tasks by specifying inputs and outputsfor each task/subtask. Department of Biomedical, Human Factors, & Industrial Engineering

19. Behavioral Verbs • ActionExample - to turn on, to monitor, to disassemble • Equipment Acted UponExample - switch, motor, display • Consequence of ActionExample - voltage display stabilized • Stimulus that Initiates the ActionExample - pilot’s command Department of Biomedical, Human Factors, & Industrial Engineering

20. Behavioral Verbs (cont) • Feedback Information Resulting form Task PerformanceExample - aircraft heading 320 degrees • Criterion of task accomplishmentExample - vehicle stopped/parked with 3 feet of marker Department of Biomedical, Human Factors, & Industrial Engineering

21. Task Analysis • Collect Information (See Table 1 Handouts) • Record Data (See Table 2, Figure 1 Handouts) • Analyze Data (See Table 3 Handouts) Department of Biomedical, Human Factors, & Industrial Engineering

22. Task Analysis Techniques • Task Data Collection Methods • Activity sampling • Critical incident technique • Observational techniques • Questionnaires • Structured interviews • Verbal protocols Department of Biomedical, Human Factors, & Industrial Engineering

23. Task Analysis Techniques cont. • Task description methods (charting and network) • Input-output diagrams • Process charts • Function flow diagrams • Information flow charts • Critical path analysis • Petri nets • Signal flow graphs Department of Biomedical, Human Factors, & Industrial Engineering

24. Task Analysis Techniques cont. • Task requirements evaluation methods • Ergonomics checklists • Interface surveys Department of Biomedical, Human Factors, & Industrial Engineering

25. Task Analysis Techniques cont. • Task description methods • Hierarchical task analysis • Link analysis • Operational sequence diagrams • Timeline analysis Department of Biomedical, Human Factors, & Industrial Engineering

26. Task Analysis Techniques cont. • Task behavior assessment methods • Barrier and work safety analysis • Event trees • Failure modes and effects analysis • Fault trees • Hazard and operability analysis • Influence diagrams • Management oversight risk tree technique Department of Biomedical, Human Factors, & Industrial Engineering

27. Task Analysis Techniques cont. • Task simulation methods • Computer modeling and simulation • Simulators and mock-ups • Table-top analysis • Walk-through and talk-through Department of Biomedical, Human Factors, & Industrial Engineering

28. HTA – A General-Purpose Task Analysis Technique • Hierarchical Task Analysis (HTA) • Developed for use in training domain (Annett et al., 1971) • Requires the analyst to establish conditions when various subtasks should be carried out to meet a system’s goals • Produces a hierarchy of operations and plans • Activities of human operator are linked directly to system requirements Department of Biomedical, Human Factors, & Industrial Engineering

29. HTA Application • For all stages of system life-cycle • Used to deal with: • Interface design • Work organization • Facilitator design • Human error analysis Department of Biomedical, Human Factors, & Industrial Engineering

30. Basic Terms • Goals Desired states of systems under human control or supervision • Tasks Methods adopted to attain the goal, in any instance, which is constrained by: availability and cost of materials; equipment and facilities demands; availability and cost of services; time constraints; legal obligations; and personnel preferences • Operations Any unit of behavior, no matter how long or short in duration, and no matter how simple or complex in structure, which can be defined in terms of its objective Department of Biomedical, Human Factors, & Industrial Engineering

31. Basic Concepts • Hierarchies of goals and sub-goals Goals can be described at various levels of detail, thereby allowing the nesting of goals (sub-goals) • Plans and the organization of sub-goals Plans specify condition when sub-goals should be carried out. Can include sequences of actions or sets of actions conditional upon time or events • Stopping rules Stop converting goals into plans and sub-operations when effort and time is no longer justified. The rule may depend on the domain or particular task Department of Biomedical, Human Factors, & Industrial Engineering

32. Task AnalysisExample of Question Categories • Design Questions • Manning Questions • Training Questions • Test and Evaluation Questions Department of Biomedical, Human Factors, & Industrial Engineering

33. Design Questions • What tasks need to be performed? • How critical is each task? • In what sequence must the tasks be performed? • What control activations are required? etc, etc, etc, etc Department of Biomedical, Human Factors, & Industrial Engineering

34. Manning Questions • How many people are required to perform the task? • What skill levels are required? Department of Biomedical, Human Factors, & Industrial Engineering

35. Training Questions • On what behavioral dimensions are the tasks performed? • How difficult or complex is each task? • What information is required to perform the task?etc, etc, etc, etc Department of Biomedical, Human Factors, & Industrial Engineering

36. Test and Evaluation Questions • What are the performance criteria for the task or job? Department of Biomedical, Human Factors, & Industrial Engineering