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Task Analysis. 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.

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task analysis

Task Analysis

Department of Biomedical, Industrial Engineering & Human Factors Engineering

what is task analysis
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

why conduct task analyses
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

when is task analysis done
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

task analysis application areas
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

task analysis application areas cont
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

task analysis application areas cont7
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

task analysis and system life cycle
Task Analysis and System Life-Cycle

From Kirwan and Ainsworth, 1992

Department of Biomedical, Human Factors, & Industrial Engineering

task analysis techniques overview
Task Analysis Techniques - Overview

Department of Biomedical, Human Factors, & Industrial Engineering

analysis procedures
Analysis Procedures
  • Mission Analysis Function Determination
  • Function Allocation
  • Task Description / Identification
  • Task Analysis

Department of Biomedical, Human Factors, & Industrial Engineering

mission analysis system requirements analysis
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

mission analysis tools
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

importance of function task analyses
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

determination of functions
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

determination of functions15
Determination of Functions

Functions - Can be

Instantaneous (Start Engine)

Prolonged ( Monitor Radar Screen)

Complex (Analyze Equipment Malfunction)

Department of Biomedical, Human Factors, & Industrial Engineering

function performance criteria
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

functional flow diagram
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

task description identification
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

behavioral verbs
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

behavioral verbs cont
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

task analysis21
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

task analysis techniques
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

task analysis techniques cont
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

task analysis techniques cont24
Task Analysis Techniques cont.
  • Task requirements evaluation methods
    • Ergonomics checklists
    • Interface surveys

Department of Biomedical, Human Factors, & Industrial Engineering

task analysis techniques cont25
Task Analysis Techniques cont.
  • Task description methods
    • Hierarchical task analysis
    • Link analysis
    • Operational sequence diagrams
    • Timeline analysis

Department of Biomedical, Human Factors, & Industrial Engineering

task analysis techniques cont26
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

task analysis techniques cont27
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

hta a general purpose task analysis technique
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

hta application
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

basic terms
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

basic concepts
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

task analysis example of question categories
Task AnalysisExample of Question Categories
  • Design Questions
  • Manning Questions
  • Training Questions
  • Test and Evaluation Questions

Department of Biomedical, Human Factors, & Industrial Engineering

design questions
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

manning questions
Manning Questions
  • How many people are required to perform the task?
  • What skill levels are required?

Department of Biomedical, Human Factors, & Industrial Engineering

training questions
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

test and evaluation questions
Test and Evaluation Questions
  • What are the performance criteria for the task or job?

Department of Biomedical, Human Factors, & Industrial Engineering