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SOME CAUSES OF ERRORS USING ANTHROPOMETRIC DATA WHEN
DESIGNlNG PRODUCTS AND WORKSTATIONS
ManuelaQuaresma,Anamaria deMoraes,D.Sc.
LEUI - Laboratoryof ErgonomicsandUsabilityof Interfacesin Human-Technology
Systems
MasterProgramin Design;CAPES
PUC/RJ- PontiticalcatholicUniversityof Rio deJaneiro
Rio deJaneiro,BRASIL
V&r& Maria Batalha Cardoso, M.Sc.
Funda@ Universidadedo Amazonas
Manau$BRASIL
When we mention anthropometry nowadays it looks a pre-historian subject. Nevertheless
people complains about dimensional errors in products and workstation with problems to the
user comfort and to the system safety. The data are available - a lot of researchwith different
population -; what is the problem? In this paper the results of interviews with designers are
presentedas an attemptto explain the reasonfor the misuse of anthropometric data andthe most
common errors applying antbropomettyto design of products and workstation.
PROBLEM
METHODS AND TECHNIQUES
There are some errors of anthropometxicapplication
in product and workstation design. Somedesigners,use
the measuresof their own bodies when designing.
Obviously this results in design errors, problems of
comfort for the user and safety for the system.
Someother designerseven knowing anthropometric
data choosemeasurementsbasedin the “averageman”
(50” percentile).
As there are not enoughresearchesin the
anthropometic data of the Brazilian population, many
designerssimply do not use any kid of data. They think
that international researcheswill not provide correct
values.However, they usepre-defmedmeasurements
published in someproduct designbooks. (e.g., 75 cm for
table heights and 45 cm for chair heights), ignoring the
compatibility of the extremepercentiles- small woman
and large man.
Literature researchto point out someevidencesof the
designers’major mistakes in applying anthropometric
data, making arrangementsfor the project, setting
products and workstations’ conformation and
dimensions.
Eight designerswere interviewed in order to
enumeratethe methods,procedures,strategiesand
referencesusedto setthe products and workstations’
conformation and dimension.
An analysis of the mistakeswas pointed out by the
authors in setting the products and workstations’
conformation and dimensions.
OBJECTIVE
Verifythe procedures,strategiesand referencesused
by designerswhen developing layouts, shapesand
dimensioningproducts andworkstations.
Verify the errors in developing layouts, shapesand
dimensioningproducts and workstations, causedby
errors and slips in the use of ergonomicprocedures
during the design activity.
RESULTS
Regardingthe application of the anthropometrics
data,the most frequent mistakes madeby designersare:
the use ofthe designer’sown body dimensionsas a
parameter,andthe use of the so-called “averageman”.
According to the designers,the lack of specific
anthropometic data on the Brazilians people is the
reasonfor inappropriate setting of dimensionsin
Brazilian products. However, the samemistake is
observedin American, English and Frenchproducts.
Nevertheless,anthropometricdata of those populations
are available. The main question is not which data of
which population the designerwill use in hi&her project,
but the use of the “average man” (Moraes, 1994).
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In the account of anthropometricdata, it is worth
quoting:
‘The properor impropersettingof dimensionsregarding
Brazilianproductsis not relatedto thelack of Braziliin
data.Thequestionis howto usethe existingdata.The
wrongutilisationof theexistingdatais worstthanthelack
of da@Amcricaoor Brazilian-that influenceseven
biggermistakes.”f.&foraes,1994).
According to Pheasant(1996), there are five
fundamentalfallacies on the use of anthropometricdata
said by designersabout projecting workstations,
furniture and products:
“1. This designissatisfactoryfor me-it will, therefore,be
satisfactoryfor everybodyelse.
2. This d&u is satisfactoryfor the averageperson- it
will, therefore,be satisfactoryfor everybodyelse.
3. Tbcvariabilityof humanbeingsis sogreatthatit cmmot
possiblybc cateredfor in anydesign-but sincepeopleare
wonderfullyadaptableit doesn’tmatteranyway.
4. Ergonomicsis expensiveandsinceproductsareactually
purchaseon appearance
andstyling,ergonomic
considerations
mayconvenientlybeignored.
5. Ergonomicsis anexcellentidea.I alwaysdesignthings
with ergonomicsin mind -but I do it intuitivelyandrely
on my commonsensesoI don’tneedtablesof dataor
empiricalstudies.”
It was possibleto confirm such ideas in statements
heard during the interviews with Brazilian designersof
products, furniture and workstation:
1) The lxoduct “satisfies” its own designer
“(. .) You havea catain piecetbatis anarchitcctoml
element,it hasto be comfortablein additionto pretty The
comfortitself givesyou no prettinessandno pieceat all.
Thebeautyitself, without thecomfort,givesyou a
sculptoreThereis a needto bringtogetba thesetwo
importantcomponents:
prettinessandcomfort,the
functionality My expcricnceis all I havebecauseI didn’t
studythis kind of thing at College.The&airs thatI’ve
beendoingarc,in principle,basedon mv own body.A
chairis meantfor manypeopleto sit on it, I don’t meana
spaceshipor Formula1 seafthosearcmadespecially
(. .)” [author’semphasis]
2) The uroduct “satisfies” the averagewrson
“(.. .) I’m concerned
with settingdimensionsthatI can
considerasanaveragedimension,they’ll neverbe ideal
Our philosophyhereis to try to do things,everyobject,
thatanavermeDemo&anouts&r, will look at andwon’t
fear.We risk doingit because
we immediatelyfeel safeto
do it. (. ..)” [author’semphasis]
THE ANALYSIS OF THE MISTAKES
It is possibleto enumerateother typical mistakes
doneby designerswhile designingthe products:
Inter-population versus intra-population differences
Moraes (1992) saysthat many designerslook up the
demographiccensusin searchfor the averageBrazilian.
It is proved by researchthat anthropomctric data may
have a bigger variability amongthe samepopulation
than betweendifferent populations, i. e., the difference
betweenAmerican and Brazilian people is smaller than
the difference betweenpeople oftwo distinct statesin
Brazil. Therefore it is worst to usethe data on average
staturefrom one northern stateto products for
populations of southernstatethan it is to use it from
Americans to Brazilians.
“The meanstaturefor some1,200samplesfrom Africa
andEuropzis 167.1cm, andthe standarddeviationof the
meansis approximalely5.6 cm.Thestandarddeviation
statureis knownfor 200of thesesamples.Themean
standarddeviationis 6.1 cm. In otherwords,variationin
total bodysizebetweenpopulationsis, ifanytbing less
thanthatwithin populations.Tildcsley(1950)examineda
numberof antbropomctticdimensionsin a similarway for
indigenouspopulationsall overtbc world. (...) In almost
everyDimensionsthevariabilitywitbin populationswas
greaterthanthatbetweenpopulations.”(Robertsspud
Mows, 1992)
Therefore, it is possibleto concludethat to use data
from Para& (a Brazilian State)in setting dimensions for
productsto Maranh~o(anotherBrazilian State)is a
bigger mistakethan to use American tables to dimension
Brazilian products.
Population’s selection/research
Mistakes in setting dimensionsfor workstations,
furniture andproducts can be causedby the use of
anthropometricdata from specific population researchamong College studentsor military subjectsfor example.
As Roebuck (1975) observes:
“The percentilevaluesusedin Apollo Projeclwerebased
in dataof theFlying Personnel incorrectresultscouldbc
expcctcdif the pcrcmtik valuesbadbeensclcctedfrom a
lessrepresentative
population,like a researchon stodcnts
or Americanarmytruck drives.”
It is saidthat the proper way to setthose dimensions
would be to use researchwith more generaldata.
As Moraes (1983) says,many authors demonstrated
(Chapanis,1962; Panero& Zelnick, 1983; Pheasant,
1986) and researchesproofed (Vital&Health Statistics,
1981)that the younger, wealthier and better-educated
populationshave bigger dimensions.Therefore,the use
of data from a researchwith studentsto design products
to an older, poorer or less educatedpopulation, may
result in damageto smaller individuals.
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Correct Variable’s Selection
Another reasonfor mistakes in setting workstations
and products dimensions,accordingto Moraes (1983), is
the choice of the variable (or variables) which will be
taken into accountwhen projecting a product. For
instance,one can frequently seethe definition of the
better place for visualisation on display windows be set
accordingto stature.The proper thing to do would be to
usethe eye level’s height andthen setthe limits for the
vision field. Projects should use specific anthmpometric
variables for eachdimensionto be set. It is necessaryto
make a chair’s function, for example, explicit. To design
a chair for a typist is different than to design one for an
auditorium.
The fallacy of the average man
One of the most common mistakes is to use data Tom
the “averageman” when designingproducts and
workstations. The project is basedon an average
supposingto satisfy the majority.
Various mistakes can be lead by the selection of
values from the percentile 50. Actually, asthe average
value is used,half of the population is damaged- at
times this half is smaller than the average(it’s the case
ofthe ranges),at other times the half is larger than the
average(in defming the spacefor the legs under a table,
for example).Moraes (1992).
Cushman(1991) recommendsthe use ofthe
percentile 95’ to establishthe products’ minimal
dimensionsinvolving spaces(clearances)andthe body
dimensionsof percentile 5“ for the pmducts’ maximum
when rangesarc involved.
Many authorsdiscussthe “fallacy of the average
man>>(Damon et &I, 1966, Moraes, 1992, 1983; Panero
& Zelnik, 1979; Pheasant,1986; Roebuck, 1975; Van
Cott, 1972). Still, somedesignerspersist on the “average
ma”” myth.
Cushman(1991) emphasiscsthat there is no such
thing as a percentile 50tbindividual, percentile 5” or a
percentile 95* individual. Thesevalues representthe
individual’s possible average,minimum and maximum
dimensions,respectively and the individual may not
necessarilyhavethem all. He/shemight alternatea
percentile 5” dimension with a percentile SO*.Quoting
Cushman:
“(...) termssuchas‘50” percentileuser’,‘5* percentile
female’,and‘95” percentilemale’usuallyreferto
percentilerankingsfor only onebodydimension.The
variabilityamongthepercentilerankingsof body
dimensionsfor the samepersonis clearlyshownin a study
of severalhanddimensions(Champney,1977).Subject#l
hadonly a 1’ percentilebandbreadthbut hada 52
percentilebandthic!mess,for example.Subject#14bada
96* percentilehandbreadthbut only a 6* percentilehand
spreadwedge.”
Thereforethe designerwill considerthe value of the
percentile’s maximum extreme or the value of the
percentile’s minimum extreme,accordingto the
product’s characteristics,the system’s functions and the
activities performed by the operator.
The importance of the Task Analysis
Onething to be consideredis that many mistakes
happenwhen designers,while projecting a workstation
or a piece of furniture, begin using ergonomics,in fact
anthropometry,without task analysis. The designer
usually begins his/her ergonomic study at the stageof
developmentinsteadofthe stageof rising data. As a
consequence,the alternative designsfor the project will
not considerthe requirements,the parameterandthe
task’s aim to the application of the anthropometric data.
ARer Porter (1995) we shall mention that “It is
essentialthat ergonomicsinput to a product takes place
throughout the designprocessbut nowhereis it more
important than at the conceptand early development
stagesof design. Basic ergonomic criteria suchus the
adoption of comfortable and effective posturesneedto
be satisfied very early on. Ifthese criteria are not
thoroughly assessedthen there is usually only very
limited scopefor modifications later on as all the other
designteam memberswill haveprogressedtoo far to
make major changeswithout considerablefmancial and
time penalties.”
Pheasant(1996) can be mentioned in relation to the
importanceof the task analysis:
“A taskanalysisis reallya formal or semi-formalattempt
to &tine andstatewhattheuser/operator
is actuallygoing
to do with theproduct/system/envimmnent
in question.
This is statedin termsof the desiredendsof the task,the
physicaloperationtheuserwill perform,the informationprocessingrequirements
it entails,the environmental
constrainsthatmightpata@ andsoon. An effectivetask
analysiswill clarify theoverallgoalsof theproject,
establishthe criteriathatneedto bc met,pointout the most
likely areasof mismatch,andsoon.”
Designerscommonly make a mistake in a product’s
project that, in spite of being directly linked to the
application of anthmpometric data,the task analysis, as
said before, is what gives the basic requirementsfor the
application ofthe anthropomctric data. It follows some
pieces of the interview relatedto this kind of mistake:
“(. .) sometimesthework is doneon theproduct’s
material,othertimeson its function,it dependson each
case,but we try to createa n&r of ideas.SpmetimesI
promotea workshop,for example,whereeverybody- I’ve
donethis abouta foodprocessor- everyonefrom my
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office get into the conceptwdisation
stage,1l&&&e
designersworkingall daylow andat theendof the dav
we havelittle modelsandideas(...)”
“(. .) webeginto havean ideaof Designhere,I mean,that
thereis a Brazilianconsumerthatwill usethis product,so
thefirst thing is to understand
this consumer’spsychology,
I mean,who is reallygoingto usethis product.Thenwe
haveto createthemostlogicalsequence
possible.
Visual& commandsthatneedno suwior intelliience,I
do this for a four war old child (. .)”
“( .) we try to beginby makhlgall our arrangements
basedme& on concevts,if it will fit the archesposition
andmeasures,
whatever,therangesinsidethepopulation
tha1w&retryhlgt0reach(...)
“(, .) manytimesa projectmaynot needan extensivetask
analysis.It maynot evenhavea task,decendiwon the
product’spmiect.I meat&therewill alwavsbe some
activitv, but, it maynot be ow,anisedasa task(. )”
“(. .) I developeda goodexampleabouttheauditorium
seat;I visitedvariousmovietbeatreswhich auditoriums
werein differentconditionsandlookedthemUT)in
catdomes.I did all thattrying to find out whatwasthat
seat’sexactfunctionandI basicallydid it by sitting on a
lotofthem(...)”
Wrong use of the standard measures
As statedearlier, many designers- out of
unawarenessor laziness- persist in using the “standard’
measuresor useexisting measuresfrom products even if
they are not correct, not consideringthe task analysis,
which would explain the requirementsto set the
product’s dimensions.Such problem can be pointed out
in the following interview:
“(. .) if theproductis goingto haveBsequence
in relation
to a previousprahlct, thenI follow the e
dimensions,or, if it’s a newproduct,I useexternal&&
like w.
At timesI applytestsan& whenpossible,I
raisesonlenmreextensivedatain speciticresearches
on
theproduct.In thatcaseI usethe client’sknowledgetoo,
whateverresearchthe clientalreadyhason thetopic and
theproduct’spublic.I alsouse,obviously,booksthat tell
mehow to adaptthis kind of pradwt.”
“(. .) 1takefor grantedthe chair’sapproximateheight,_a
chair’smediumheightis 45,a table’saverazehei& is 75.
somethhw areaIre& standard&d(. )’
“(, ,) ifit is aboutan industriallyproducedchair,you have
to usethatchair’smediumstandard”
CONCLUSION
Moreover it is obvious the lack of task analysis as an
usability tool. Somedesignersusetask as a buzzword.
The main referencesare the dimensionsof existent
products, the colleague’sopinion. They also look for data
in the literature that &en are specific for othershumantask-machine-systems.
The designers-it is amazing - are still designing for
the averageman!!
Those are problemsthat the use of Anthropometric
CAD will not solve.
Even in the post modem agedesignersneedto be
trained in how to design considering ergonomicsfor
better product usability. Part of this implies how to use
anthropometricdata after ergonomictask analysis.
BIBLIOGRAPHIC
REFERENCES
CHAPANIS, Alphonse Research Techniques in Human
Engineering. Baltimore Johns Hopkins, 1962.
CUSIIMAN. Wilian H: ROSENBERG. Daniel. HumanFactor in
Prod,,c&ig,.
A&terdam: Else&r, 1991.
DAMON, Albert; STOUDT, Iloward W.; MCFARLAND, Ross A..
The Human Body in Equipment Design. Cambridge: Harvard
UniversitypreSs, 1966.
MORAES, Anantia de.Pesquisa Co~orma@o da Inte~$ace
Hornem-Tore@Mciqwina: Awmjo Fisico de Subsistemase
Dimensionumento e Desenvoh%nento dos Componentes; 0 Use
de CADS de Antrouometia, Rio de Jan&m: ESDVLIERJ/CNT’a
APB, 1995-1996.’
MORAES, Anasnaria de. Diazn6stico Erzo&nico do Processo
Cmu&cioml
do Sist& Homem&dquina de Tmnscrip50 de
Dados: Posto de Trabalho do Digitador em Twminais
InfomrarrZados de En@& de D&x. Tese de Doutorado IBICTkC0luFR.l -Area Maior: Ci&xia da Infomq~o. Rio de
Janeiro: ECO/VFRJ, 1992.
PHEASANT, Stephen. Bodyspace: Anthropome@, Ergonomics and
Design of Work. 3. ccl London: Taylor&Francis, 19%.
PHEASANT, Stephen. B@wpace. London: Taylor & Francis, 1986.
PORTER, J. M. et al. Computer aided ergonomics and workspace
design. Wilson, J. R; Co&t, N. G. Evabxition of human work: a
pmctid ergonomics methcdologv. London, l‘sylor & Francis,
1995. 2d ed. 1I,34 p. pp 574 -620.
ROEBUCK Jr., 1. A.; KROEMER, K. H. E.; ‘THOMSON, W. G..
Xngineeting antttmpomelry methods. New York: John Wiley,
1975.
VAN COTT, Harold P.; KEVKARE, Robert G.. Human En@zeering
Guide toEquipmmfDesig,t Was~m
D.C.:USGovernment
PrintingOfike, 1972.
The designer’s speechesare explicit. During the
designprocessthey do not apply ergonomic in the early
stageof project development.
“ITAL &HEALTH STATISTICS. Height and weight ofad&
ages 1%74years by socioeconomic ondgeogmphic variables.
Hyattsville(USA): U.S. Department of health and human
services, 1981.
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