1. Copyright  2003 by Dr. Gallimore, Wright State University Department of Biomedical, Industrial Engineering & Human Factors Engineering Task Analysis

2. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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.

3. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

4. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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)

5. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

6. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

7. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

8. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis and System Life-Cycle Human Factors Issue Concept Spec. System Def.DesignDeployOps and Maint Allocation of function BestPoss Check Person specification ReviewCheck StaffingToo soonBestPossCheck Task and interface design Too soonBest Skills acquisition Too soon Best Check Performance assurance Constantly From Kirwan and Ainsworth, 1992

9. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Techniques - Overview CategoryDescription Task data collection techniques Primarily used for collecting data on human- machine interactions, and which then feed into other techniques Task description techniques Structure collected information into systematic format. Formats may then serve either as reference material to enhance understanding of human –machine involvement Task simulation methods Aim at compiling data on human involvement to create a dynamic model of task execution. Provides generic model of task performance (in time and accuracy) based on individual task data Task behavior assessment methods Identify what can go wrong that can lead to system failure, and often deal with hardware, software, and environmental events as well as human errors. Derived from engineering risk assessment domains Task requirement evaluation methods Assess adequacy of facilities which operator(s) have available to support task execution, and directly assess the interface and facilitator designs (e.g. training manuals)

10. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Analysis Procedures Mission Analysis Function Determination Function Allocation Task Description / Identification Task Analysis

11. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

12. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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.

13. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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.

14. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

15. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Determination of Functions Functions - Can be Instantaneous(Start Engine) Prolonged( Monitor Radar Screen) Complex(Analyze Equipment Malfunction)

16. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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.

17. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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.

18. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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 are operator or maintainer activities; and by the hardware/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 outputs for each task/subtask.

19. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Behavioral Verbs Action Example - to turn on, to monitor, to disassemble Equipment Acted Upon Example - switch, motor, display Consequence of Action Example - voltage display stabilized Stimulus that Initiates the Action Example - pilot’s command

20. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Behavioral Verbs (cont) Feedback Information Resulting form Task Performance Example - aircraft heading 320 degrees Criterion of task accomplishment Example - vehicle stopped/parked with 3 feet of marker

21. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Collect Information (See Table 1 Handouts) Record Data (See Table 2, Figure 1 Handouts) Analyze Data (See Table 3 Handouts)

22. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Techniques Task Data Collection Methods –Activity sampling –Critical incident technique –Observational techniques –Questionnaires –Structured interviews –Verbal protocols

23. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

24. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Techniques cont. Task requirements evaluation methods –Ergonomics checklists –Interface surveys

25. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Techniques cont. Task description methods –Hierarchical task analysis –Link analysis –Operational sequence diagrams –Timeline analysis

26. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

27. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Techniques cont. Task simulation methods –Computer modeling and simulation –Simulators and mock-ups –Table-top analysis –Walk-through and talk-through

28. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

29. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering HTA Application For all stages of system life-cycle Used to deal with: –Interface design –Work organization –Facilitator design –Human error analysis

30. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

31. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

32. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Task Analysis Example of Question Categories Design Questions Manning Questions Training Questions Test and Evaluation Questions

33. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

34. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Manning Questions How many people are required to perform the task? What skill levels are required?

35. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering 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

36. Copyright  2001 by Dr. Gallimore, Wright State University Department of Biomedical, Human Factors, & Industrial Engineering Test and Evaluation Questions What are the performance criteria for the task or job?