Lecture 20: Operational Analysis

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Lecture 20 Operational Analysis

• Readings Chapanis (1996), chapter 4.
• http//www.fas.org/spp/military/docops/usaf/2020/o
  ps-anal.htm

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Goals

• Introduce the human factors methods required to
  support the basic system development activities
  of
• analysis,
• design,
• testing.
• Standards, Guidelines and Principles cant do it
  all

3
Human Factors Methodologies

• protect (to some extent) against subjectivity and
  narrow-minded thinking.
• document the rationale behind a human factors
  intervention or design process.
• provide a method of analyzing systems.
• yield data about human performance.
• generate predictions (sometimes useful) about
  human-system performance.
• provide a basis for evaluating whether or not
  performance using a human-machine systems meets
  design criteria.

4
Applied research

• looks at more specific situations.
• asks the question, "Can people do this exact
  task under these special conditions?
• e.g., "Can sonar operators monitor sonobuoys
  from a helicopter better with a 4- or an
  8-channel receiver?".
• "What information, what work product, does this
  method provide that I can use in the design of
  some specific thing?"

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Operational Analysis

• "An operational analysis is an analysis of
  projected operations to obtain information about
  situations or events that will confront operators
  and maintainers in using a new system. It
  typically contains scenarios, verbal descriptions
  of events, and summarizes anticipated
  operations, assumptions, and environments."

6
Inputs for Operational Analysis

• information in RFPs (requests for proposals)
• planning documents
• system requirements provided by customer
• system requirements provided by experts

7
Outcomes/Deliverables

• list of system operational and maintenance
  requirements
• Descriptions of assumed operations
• list of operations that appear feasible and those
  that may overstress the system
• list of environmental factors that may affect
  system performance
• list of constraints, e.g. personnel and training,
  that may affect system performance
• list of foreseeable failures and evaluations of
  the consequences of those failures

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Analysis of Similar Systems

• One or more observational methods are used to
  discover salient features of systems that are
  similar to the one under consideration, with the
  expectation that this will provide useful
  information for design.

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Inputs for Analysis of Similar Systems

• Structural observations
• Interviews
• Questionnaires
• Activity analyses
• Critical incident studies
• Accident investigations

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Attributes of Interest

• Data on the operability of the older system
• maintainability of the older system
• Numbers of people required to staff the system
• Skills required to operate and maintain the
  system
• Training required to bring operators to
  proficiency
• problems encountered in the design of the system
  
• Problems encountered by personnel in using the
  system

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Places to find Required Information

• productivity records
• maintenance records
• training records
• accident or incident reports

12
Data Collection
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Critical Incident Analysis

• Mistakes and near-mistakes in reading an
  indicator
• Mistakes and near-mistakes in using a control
• Mistakes and near-mistakes in interpreting an
  instruction

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Analysis of Control Errors (1947)

• Confusing controls with each other 50
• Control adjustment problems (slow, quick,
  incorrect) 18
• Forgetting 18
• Failure to check, unlock, or use at proper time
• Reversal (moving control in wrong direction) 6
• Unintentional activation 5
• Inability to Reach 3

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Function Flow Analysis

• Identify sequence of functions/actions performed
  by system
• Uses information from operational analyses,
  analysis of similar systems, or activity analyses
• Start with system objectives -gt identify
  functions
• Expand top-level functions into lower levels
  containing more information

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Simple Function Flow (Meal)

• Plan meal
• Obtain food
• Prepare meal
• Consume meal
• Clean and store

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Zero-Order function flow chart (top level)

• 1. Prepare and present flight briefs
• 2. Assume pre-launch posture
• 3. Perform pre-liftoff function
• 4. Perform liftoff function
• 5. Perform transit out function
• 6. Perform selected tactical function
• 7. Perform transit back function
• 8. Perform recovery functions

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First-order function flow for Prepare and
present flight briefs
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Second order function flow

• 1.1 Prepare mission brief
• 1.2.1 Obtain briefing information
• 1.2.2 Present mission data to crew
• 1.3 Review mission preparation

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Exercise

• Prepare a functional flow diagram showing the
  steps involved in preparing for and taking a
  vacation trip by automobile. Carry out your
  diagram at least to second-level functions.

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Conclusions

• Operational Analysis examines how the system will
  be used. Identifies issues and problems and
  generates recommendations for design that
  supplement standards, guidelines, etc.