Anthropometry

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Anthropometry Workspace Design
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Static Anthropometry

• Fixed structural dimensions of the body
• Height, arm length etc.

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Workspace Anthropometry
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Percentiles for Normative Population
Side View Standing
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Male
Female
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3
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Use of the Normal Distribution

• Properties of the Normal Probability Curve
• Percentiles Standard Scores, T-score, Hull score

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Arbitrary Scores Scales

• T-scores
• Mean 50, sd 10
• Hull scores
• Mean 50, sd 14
• Stanine scale
• equal width of categories
• nine categories
• Each category 0.5 sd wide
• Categories 1 9 open ended

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• STANINE chosen for O-SCALE system based upon
  number of categories and equal width of categories

Stanine Category 1 1 2 2 3 3 4 4 5 5 6 6 7 7 8 8 9 9
Percentage of Normal Distribution within Category 4 4 7 7 12 12 17 17 20 20 17 17 12 12 7 7 4 4

Boundary Z-Scores Boundary Z-Scores -1.75 -1.75 -1.25 -1.25 -0.75 -0.75 -0.25 -0.25 0.25 0.25 0.75 0.75 1.25 1.25 1.75 1.75  
Boundary Percentiles Boundary Percentiles 4 4 11 11 23 23 40 40 60 60 77 77 89 89 96 96  
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Use of the NormalDistribution

• Area under the curve from 0 to Z
• Only absolute z-scores needed because the curve
  is symmetrical
• what percentage of the population is between two
  given z-scores

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Constraints Criteria

• Constraint
• an observable characteristic of humans that has
  consequence upon design
• Criterion
• a standard of judgment against which the match
  between user and artefact may be measured

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Criteria

• Primary Comfort, safety, efficiency
• Secondary numerous low-level criteria needed to
  satisfy the primary criteria

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Dynamic Anthropometry

• Reach or clearance under functional conditions
• Range of joint movements
• Strength measures
• Dynamic data often specific to design problem

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The Average Person

• The average person does not exist but is the most
  probable member of the population
• Chances of encountering an individual who is
  average in a number of dimensions is extremely
  small
• Individual can not be 95th percentile in all
  measures

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Bertillionage

• Clerk with the French Surete in late 19th century
• Catalog of seven anthropometric measures of all
  criminals measured to give unique identification
• Finger printing

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Bertillionage

• Clerk with the French Surete in late 19th century
• Anthropometrical signalment
• Catalog of anthropometric measures of all
  criminals measured to give unique identification
  to identify repeat offenders
• Finger printing

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Designing for the Majority

• 5th and 95th percentiles are often used
• What are the consequences for the 10 excluded?
• Is the user population easily defined?

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Four Cardinal Constraints of Anthropometrics

• Clearance
• Headroom, elbowroom, legroom, handle apertures.
  Define the minimum acceptable dimension of the
  object. 95th percentile
• Reach
• Ability to grasp and operate controls. Define the
  maximum acceptable dimension of the object. 5th
  percentile

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Four Cardinal Constraints of Anthropometrics

• Posture
• Relationship of dimensions of working surface to
  those of the user may determine posture. Large
  and small equally important
• Strength
• Strength imposes a one-way constraint. 5th
  percentile usually

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Multiple Constraints

• Using more than one constraint will cause an
  increase in the percentage of the population
  excluded
• Measures are not perfectly correlated