Anthropometry & Workspace Design

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

Workspace Anthropometry

Percentiles for Normative Population Side View Standing 1 Male Female 2 3

Use of the Normal Distribution Properties of the Normal Probability Curve Percentiles & Standard Scores, T-score, Hull score

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

STANINE chosen for O-SCALE system based upon number of categories and equal width of categories Stanine Category 1 2 3 4 5 6 7 8 9 Percentage of Normal Distribution within Category 4% 7% 12% 17% 20% Boundary Z-Scores -1.75 -1.25 -0.75 -0.25 +0.25 +0.75 +1.25 +1.75   Boundary Percentiles 11 23 40 60 77 89 96

Use of the Normal Distribution 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

Constraints & Criteria 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

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

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

“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

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

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

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?

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

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

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