1.1a Anthropometrics

Adjustability

Designing for adjustability means that provision is made within the design for adjustments to accommodate the anthropometric variability between members of the user group adjustability avoids anthropometric mismatch adjustments can be performed using mechanical, electrical, pneumatic or hydraulic means

Design for children

Many products developed for children will also require careful consideration of anthropometric data and ergonomic design specifically, the designing of computer furniture for primary school age students is a complex issue requiring consideration of a large percentile range, 5th-95th, across genders and encompassing significant age variation appropriate design would encourage correct posture, reduce fatigue, facilitate ease of use and avert-term health problems

Range considered for adjustability

When considering adjustability, the percentile range generally considered appropriate is the 5th percentile of females and the 95th percentile for males because of the overlap in dimensions of the male and female population, this regime would account for 95% of the user population

Gender and Anthropometrics

Within a gender, the 5th through 95th percentile range will cover 90% of people, only the upper most an lower most are outside of the range (in mixed gender it covers 95%)

Culture and Anthropometrics

anthropometric data is intended to represent the measurements of the nude body cultural restrictions, however, may also prevent the ability to obtain data from unclothed subjects in order to adjust for this situation investigators make allowances for the type and thickness of the clothes worn

Percentile Ranks

are commonly used as a tool for interpreting anthropometric data because of their straightforward ease of use care must be taken when using percentiles, however, when considering distributions at the extremes of populations in these regions, small changes in percentile values can mean large differences in the data which is being reported

Skinfold calipers

are used to determine the amount of subcutaneous body fat by gently pinching a fold of skin two regions have been standardized for testing; the triceps and sub-scapular skinfold although skin thickness is generally uniform over the body the pattern of fat deposition is not

Percentile Ranges

are used to measure dispersion within a sample population a spread between the 95th and 5th percentile would be expressed as: P95 - P5 Percentiles shown in anthropometry tables determine whether the measurement given relates to the 'average' person, or someone who is above or below average in a certain criterion

Primary Data

collected by the designer, who performs anthropometric measurements on the proposed user group because they are proposed on a user group it related directly to the intended population

Secondary Data

collected from a database of anthropometric measurements such as databases are often national in nature

Example of 50th percentile design

development of crash test dummies crash test dummies used to use only male data for testing cars 95th percentile male dummy (heavier and taller than 95% of human males) used by aviation industry to test emergency situations involving; ejection seats, aviation helmets and pilot restraints due to lack of vehicle data available for occupants other than a male driver, crash test dummies have now been developed for women and children the development of crash test dummies to now incorporate percentile range is a good example of where particular user groups are identified within a very specific design context

Limitations of design in 5th to 95th percentile

even though designing for the mean seems to make sense, the majority of people are actually excluded i.e. outside the range of this group designing for this average user can also be difficult if the range of users cross age and/or gender boundaries

Reach Envelope

for a range of users is defined as a three-dimensional space reach of individual's arm when using a desk (important limiting factor) reliable data is required to develop an appropriate response to reach envelopes when considering a broad population sample data may be gathered from anthropometric tables, dynamics measurements or through the use of software simulations. Data can be affected by such restrictions as clothing operational areas of an individual from the axis of bilateral symmetry

Proportions (Multivariate Analysis)

human dimensions are not always in the same proportion, and a tall person can have short arms or short person have proportionately long arms Multivariate analysis is used to account for all variations and means that more than 5% of the population may be excluded on one or more dimensions if using the 5th to 95th percentile range

Example of Percentile Range (height)

if a group of adults is sampled, many will have data recored showing them to be around the same height some will be appreciably taller while others may be shorter the 'same height' group will be near the average or 'mean' and will be displayed in anthropometry tables as the 50th percentile. the 50th percentile in this case identifies the most likely height of an individual within the group

Standardization of measurements (methodology)

important for measurements to be undertaken in a methodological, standardized manner that allows confidence in the data collection WHO recommends a strict and standardized quality assurance protocol involving extensive staff training from experienced instructors, constant supervision and monitoring of data collection techniques as well as frequent testing and calibration of equipment

Anthropometry in design

in a design context, determining which percentile value or range may be critical to success depends on what is being designed and for whom the design needs to cater age, gender and even cultural background can affect ergonomic design

Structural/Static Anthropometry

includes data from measurements such as those made between joints data is recorded using standardized equipment such as calipers easy to collect because the subject is not moving height, weight, and data related to various body structures are included

Functional/Dynamic Anthropometry

includes data obtained while the subject is moving while quantitative data is more difficult to obtain, is often greater use because it demonstrates the range and ease with which movements can be made reaction times, reach arcs, grip strength, etc are all exmaples of dynamic data

Frankfort line

is a line connecting the ear hole with the bottom of the eye socket

Sitting Height Table

is a modification of the sadiometer and us used to measure vertical distance from the floor or seat to the top of the head. seated in upright position

Law of distribution

large number of men of a homogenous population are measured, and arranged to groups accordingly, it becomes evident that the individuals are related to one another by law of distribution a central type if represented by the most numerous group, the adjoining groups become less and less numerous in both directions shown by a binomial curve, where the abscissa (measured from an origin on the left) represent the heights of the men, and the ordinates the relative numbers of men corresponding to each heigh

Instruments for data

main criteria of instruments is that they are calibrated and are of sturdy design to ensure they provide reliable results

Example of Adjustability

most cars incorporate systems to adjust seat height and steering wheel position office chairs allow height and back rest tilt adjustment

Reliability of data

quality of data is important when determining reliability of any inferences or relationships from data sets determinations of height and weight can be the most reliable and easily gathered data sets body fat data gathering using skinfold calipers, however can often be unreliable over a population sampling

Percentiles

refer to 100 equal groups into which a sample population can be divided according to the distribution of values of a particular variable

Example of Product using only 95th percentile

standard architectural doorway the tallest people should be able to negotiate the opening the 5th to 50th percentile people being smaller in stature would naturally be catered for in this design as well

Design for more types

the commonly chosen design range of 5th-95th percentile of a population is a trade-off that allows for the inclusion of almost everyone in a design context and only excluding the extremes the practise for catering a larger percentile range is often called 'design for more types' traditionally using a 5th-95th percentile is deemed to provide the best coverage without being skewed by extremes i.e. the greatest 5% and the least 5% in the data range consumers outside this range often have to seek customized solutions to meet their needs product designed to meet these requirements would include furniture, household appliances, one size fits all free-size clothing

Con of Multivariate Analysis

the cost of accommodating all possible combinations increases dramatically past his range and in most situations is not justified

The World Health Organization (WHO), definition Antropomtry

the singly most universally applicable, inexpensive and non-invasive method available to access the size, proportions, and composition of the human body

Anthropometry

the study of human properties such as height, mass and volume and is used extensively in the design of consumer goods

New method of collecting data

traditionally measurements were taken manually but in recent years video has also been proven to be an effective tool for gathering data

Stadiometer

used to measure vertical distance from the floor to the top of the head of a person standing a horizontal headboard is attached to a vertical track. The subject to be measured is placed against the vertical scale and the headboard is moved down until it touches the head. Height is then read from the scale or recorded from a digital read-out.

Example of Product using only 5th percentile

vehicle controls where ease of reach would be the determining constraint here data as low as the 5th percentile may be required to gather in a sample population including those with the shortest reach