Anthropometric Data Survey: Methodology and Statistical Compilation / Significance

Content

1. Anthropometric data survey

2. Postural consideration for structural and functional dimensions

3. Procedure: Data collection and treatment

4. Direct methods

5. Measuring equipments (commonly used)

6. Indirect methods

7. Accuracy of measurements

8. Subject and sample size selection

Data collection methodology

Practicing designers and others use ready references and thereby arrive at varied human dimensions in design contexts.Sometimes some data might need to be generated for some specific design application and for that the methodology of the general survey and statistical compilation may be of relevance to

Postural considerations for structural and functional dimensions

Those physical human body dimensions which have an impact on design dimensions are static when structural, and dynamic when functional. Structural body measurements include direct measurements of various body parts; say heights, lengths, depths, breadths and the circumferences of head, neck, trunk, hands and legs in some standard positions. As standard practice, the collection of body structural data in static body positions is easier than the collection of body functional data in dynamic body positions.

For static dimensional measurement purposes, the subject should stand in an erect, balanced posture looking in front, with head and chest up, hands hanging in their normal position with palms comfortably stretched and legs straight with heels almost together. In a sitting posture, the subject should sit on a seat at the height of the popliteal level, so that his things can

ergonomic practitioners, researchers and students.
The following would help in understanding the procedure and becoming acquainted with the statistical implications of anthropometric data as used in design, in general.

rest flat on the seat surface with a knee angle of 90 degrees. The trunk position should be straight, erect and vertical, perfectly at a comfortable 90 degree angle at the hip, with the neck straight, looking horizontally forward. The arm should be in a normal lateral hanging position with a degree elbow angle, keeping the forearm horizontally forward, with the palm spreading.

In other commonly used Indian postures, say sitting on the floor cross-legged and in a squatting posture, the trunk will be in a comfortably upright vertical position, with head up. In the case of dynamic body dimensional measurements, as the body functional contexts vary, comfortable work postures should be maintained and measurements of body parts in such positions should be taken with extension and flexing movements so that various reach values in different positions are normally taken care of.

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Procedure : Data collection and treatment

Measuring dimensions: Technique

The measuring methods as demonstrated in the video and illustrations presented herein may be followed with the relevant experimental set up using

(A) anthropometer set (e.g., rods marked in part millimeter scale are joined together to make a single scale from 0 to 200 cm and using various sliding branches),

  (B) anthropometric board and other relevant devices specifically developed for suitability to measure respective measurements.

Data treatments - relevant calculations are to be followed.

Data usage- principles and thumb rules are to be maintained.

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Anthropometric rod

Measuring methods

Both direct and indirect measuring procedures are followed to collect anthropometric data from selected subjects in a particular population.

Direct methods
Direct body measuring instruments mostly used are:

• A common set of anthropometric instruments.
• Anthropometric board with grid marks.
• Some other special measuring devices such as adjustable foot measuring instruments box and blocks, marked conical devices for measuring the grip diameter and inner circumferences.

Measuring Equipments
(commonly used)

A. Anthropometeric instruments, clockwise from top: anthropometric rod and branch set; curved branches for anthropometer; spreading calipers; sliding compass,

B. Weighing scale; grip cone; height adjustable stool,

Caliper

Direct and indirect body measuring procedures may be considered separately or taken both simultaneously, depending on the context of the dimensional requirement and the suitability of the study.

• Special various diameter holes containing panels for measuring finger diameter etc.
• For circumferences, non-stretchable tapes are used. For specific measurements specific devices may also be created

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C. Measuring the grip diameter with a specially marked conical device.

Chest caliper

Anthropometric rod  

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  Indirect methods

Indirect measurements may be taken through photographic methods, using still photography and filming the whole body and/or parts from different angles against a marked grid background, or superimposition of a grid on the photographed human body. To guard against parallax errors - problems where the actual dimensions may change - much care must be taken or dynamic measurements, subjects are asked to

perform for the intended tasks in actual and/or simulate situations and the relevant measurements are taken. Subjects may leave some marks denoting the limits to which they can stretch their limbs in a comfortable position. Different types of grids are also used to measure these marks. Recent development in this field is using whole body scanner that gives digital dimensions.

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Accuracy of the measurements

For cyclic dimensional changes as in the chest, the inflated circumferences must be considered if the aim of the design is to make a rigid armor type of equipment covering the body. Depending on the design when the total surface circumference is required, the tape should be held loosely. Tightly pulled tape may be used only to avoid excess flabbiness of skin folds etc. If there is no specific purpose, the average measurements of both loose and tight tapes would be appropriate.

Generally the measurements of single dimensions are taken twice. If there is any difference, the average is to be recorded, because though the subject is in a static posture, due to various body rhythms, landmark positions may vary. Whatever procedures are used, before starting the

 intended landmarks on the body or the reach limits should be decided upon and standardized, and all the researches of a study/survey team should follow the same methods.

The measurement procedure should be practiced earlier and while actually measuring the subject, one should not take much time. Otherwise body positions and reach points would change.

After each and every measurement is taken, it should be noted down in a pre-design schedule. Compilation of collected data should be done from there. Direct entry in the data processing machine without using an intermediate data schedule during the study could be done in order to reduce time and effort. But if entry mistakes are made theses would be very difficult to rectify.

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Subject and sample size selection

The larger the random sample sizes of the survey, the greater the accuracy and reliability. Normally, the users of anthropometric data, use ready reference sources. But if some typical data not readily available, then small survey on the

population of intended users may be conducted For that, samples of roughly 20% large sized, 20% small sized people and 60% at random may be collected from the study group, in order to avoid missing the data covering the extreme ends - lower and higher sides of the range.

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