Two types of Work Analysis

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Two types of Work Analysis

• Normative and Descriptive approaches to Work
  Analysis from Chapters 3 4
• Vincente 1999
• Mark Little
• 9/26/07

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Work Analysis

• Normative
• Prescribe how a system should behave
• Descriptive
• Describe how a system actually behaves in
  practice
• Formative
• Specify the requirements that must be satisfied
  so that the system can behave in a new, desired
  way.
• Also called Predictive

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Normative Approaches

• First generation
• Provide a benchmark for how workers should behave
  in different situations
• Examples
• Tayloristic work methods analyses (Taylor, 1911)
• Tradition Human Factors task analysis (R.B.
  Miller, 1953)
• Early GOMS (Goals, Operators, Methods, Selection
  Rules) analyses (Card, Moran, A. Newell, 1983)

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Task Analysis

• The point of doing any kind of work analysis is
  to derive implications for systems design
• 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
  system goal.

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Levels of Task Analysis

• Levels are based on the desired precision
• 1. Input Output
• 2. Sequential Flow
• 3. Timeline

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Level 1. Input-Output

• Inputs that are required to perform a task
• Outputs that are achieved after it is completed
• Constraints that must taken into account

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Level 2. Sequential Flow

• More specific
• A goal state with a sequence of actions for
  getting to the goal
• The temporally ordered sequence of actions that
  is required to complete the task.
• Read odometer
• Read odometer at last fill up
• Calculate difference

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Level 3. Timeline

• More specific still
• A sequence of actions, each with a particular
  duration
• Identify a temporally ordered sequence of actions
  that is required to achieve the task, with
  duration estimates for each action.
• 0-1s read odometer
• 1-2s read odometer value at last fill up
• 2-3s calculate the difference

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Levels and Approaches

• Level 1
• Based on constraints
• Level 2
• Level 3
• Based on instructions

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Task Analysis

• 2 Types
• Constraint based
• Weakness not well suited to the demands
  associated with unanticipated events.
• Instruction based
• Weakness limited in their ability to identify
  comprehensively the information requirements in
  complex sociotechnical systems.
• Instruction is more prevalent

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What this means for the worker

• Instruction based approaches
• More detailed Less decision making for the
  worker
• Simply follow the work flow
• Constraint based approaches
• More decisions are made by the workers
• Less decisions about work flow are made by the
  analyst
• Decision making seems to be a key factor in
  worker health

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What else this means for the worker

• Instruction based approaches
• Very little variability in worker action
• Perhaps only one way of doing something
• Constraint based approaches
• Great deal of variability in worker action

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What this means for the work

• Instruction based approaches
• More detailed guidance
• Less human error
• Constraint based approaches
• Minimal guidance
• More likely to lead to human error

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What this means for devices

• Instruction based approaches
• Device-dependent
• Content and form of analyses change as a function
  of the interface and automation that workers have
  available to perform the task
• Constraint based approaches
• Device-independent
• Describe properties of the task, rather than
  properties of how to do the task with a
  particular device.

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Advantages of each approach

• Instruction based approaches
• More guidance
• Less chance of human error
• Constraint based approaches
• More discretion to workers
• Fewer assumptions about the properties of the
  devices
• Greater variability in action
• More chances to learn and better chances of
  coping with unusual circumstances

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Types of Systems

• Work happens within systems
• 2 types of systems
• Open system
• Subject to unpredictable influences that are
  external to the system
• Closed system
• Completely isolated from the environment

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Task Analysis within Systems

• Within a closed system
• The more a system is closed, the more it is
  conducive to Instruction based approaches
• Within an open system
• Because of the unpredictable external
  disturbances acting on the system it will not be
  possible to accurately preidentify the different
  flow sequences or timelines that lead to the
  satisfaction of a goal.
• In a situation like this Constraint based
  approaches allow workers to better adapt to the
  disturbances.

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Instruction based Approach

• Open System Example
• Fast food computer system for cooks

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Conclusion Instruction vs. Constraint

• Our conclusion was that instruction based
  analyses are not very useful for systems that are
  substantially open to unpredictable disturbances.
  Complex sociotechnical systems clearly fall into
  this category, as do many other simpler work
  environments

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Constraint based approaches

• Not perfect though
• There are some situations in which even the
  specific goal is not identified before hand
• Task analysis
• Event-dependent

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Need something more

• Work Domain Analysis
• Represents the structure of the controlled system
• Not what workers do, rather what they do it on

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Comparisons between Procedural Survey
Knowledge
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Comparisons BetweenTask Analysis Work Domain
Analysis
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Work Domain Analysis

• Disadvantage
• They don't tell workers what to do
• Advantage
• Flexible because they provide information that
  can be used to generate an appropriate response
  to a novel situation
• They have a broader scope
• What the system is capable of

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The Answer

• ...because they have complimentary strengths and
  weaknesses, it would be useful to include both
  work domain analysis and constraint based task
  analysis techniques in a single, integrated
  framework for work analysis.

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Descriptive Approaches

• Descriptive Approaches seek to understand how
  workers behave in practice.
• Field studies
• Practical challenges workers face
• Practices workers have developed to cope

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Descriptive Approach examples
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Situated Action

• purposeful actions are inevitably situated
  actions that are responding to local
  interactions contingent on the actor's particular
  circumstances
• Actual behavior may be quite different than the
  rationalized ideal set forth by normative methods

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Recognition-Primed decision making

• Using ones experience to recognize situations and
  associate that situation with a relevant action
• Efficient
• Timely

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Activity Theory

• Goal Directed Activity
• Characteristics
• Influence of tools
• How people interact and learn from each other
• How practices have changed over time
• Understanding human skill and expertise
• Actions are situated

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Distributed Cognition

• Knowledge and information processing are not
  confined to the brain
• Distributed spatially
• Individuals
• artifacts
• Distributed temporally
• History of a culture

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Problem

• From Descriptive Analysis to Design Implications

If we conduct a descriptive work analysis to
understand workers' current tasks, we will
identify requirements that could be used to
design a new artifact. However, once this
artifact is introduced into the workplace, new
possibilities for work practices are created,
thereby shaping workers' practices
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Two ways to get around the Task-Artifact cycle

• Rapid Prototyping and Iterative User Testing
• Prototype
• Evaluate
• Iterate
• Scenario-Based Design
• Envision what it might be like to interact with a
  device that has not yet been designed

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Conclusion Work Analysis

• Work Domain Analysis
• Information requirements
• Unfamiliar / Unanticipated events
• Constraint-based task Analysis
• Information requirements
• Achieve anticipated goals with flexibility
• Strategies
• Historical Practices
• Social Organizational Factors
• Work across individuals Teams
• Worker's Competencies
• Expertise