ANALYSIS OF ELEMENTAL MOTION TIME VALUES IN A SIMPLE ASSEMBLY OPERATION

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DOCTORAL DISSERTATION SERIES TITLE

AUTHOR

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UNIVERSITY. DEGREE

PUBLICATION NO. II

'I'I'I11! 21

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y UNIVERSITY MICROFILMS ANNAtBOR • MICHIGAN

ANALYSIS OF ELEMENTAL MOTION TIME VALUES IN A SIMPLE ASSEMBLY OPERATION C liff o r d E. S c o tt - T h e sis (P h .D .) Purdue U n iv e r s ity , 1942 Techniques o f m otion stu dy a n a ly s is were used in t h i s stu-i;

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TABLE OF CONTENTS (C -.nL’ 13- -o I n d i v i d u a l l i f fe ren c® - i n P e r f o r m in g F l e n e n + e l M o tio n s R elir b i l i t - y C o w n e ris e r

o f

o f

Ver-

ru res

f i n ~le .-nd Tvo—H-nd ? e rfo r:r.:r.c e

E f f i c i e n c y o f T~o—H-nd P e r f o r m s n e e P o s s i b l e A n rs lic ;-tio n s t c T e s tin g : P r o c e d u r e s Jinn!1ic - t i o n o f T5/ e r P e 're I o - e d f o r C hrr,ter_V 12 or*?''

Cone1 n rio n.e . . . . . . . . . .................

?9

• • « • * . . . . .. . . .

A neendix A D e f i n i t i o n s -nf T h e r b l l f s A'nr' e r r' i r B

T h i s P e s “''rcfc

•••«•»*••«»» ..............

I n d i ’d d r '''' P. c ''v‘n’~ o f +h>e One—hund^^d 'Pub "eci e . . . . . . . .

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CHATTHR I IifXTlODUCTION .X13 PROBLHii

\

A n a l y s i s o f i n d u s t r i a l jo b s i n t o c o n v e n i e n t e l e m e n t s o r d i v i s i o n s h a s b e e n s t a n d a r d p r a c t i c e f o r some t i m e .

Such d i v i s i o n s a r e u s e d f o r

c o s t a n a l y s i s , t i n e s t u d y , j o b s i n . p l i f i e a t i o n , jo b r a t i n g , , wage s e t t i n g and t r a i n i n g p r o c e d u r e s .

The s p e c i f i c n a t u r e o f th e a n a l y s i s v a r i e s ,

d e p e n d in g upon how t h e f i n d i n g s a r e t o be u s e d . F . D. and L. I... G i l b r e t l i (2) u s e e i g h t e e n e l e m e n t s o r " t h e r b l i g s " t o d e s c r i b e what an o p e r a t o r a c e s i n p e r f o r m i n g a t a s k .

T h i s l i s t con­

s i s t s o f s e a rc h , f i n d , s e l e c t , g r a s p , t r a n s p o r t lo a d e d , p o s i t i o n , assem b le, u s e , d is -a s s e m b le , in s p e c t, in s p e c t, p r e - p o s itio n , r e le a s e lo a d , t r a n s ­ port

e rip ty , r e s t f o r o v erco m in g f a t i g u e , u n a v o i d a b le d e l a y , a v o i d a b l e

d e l a y , p l a n , and

h o ld .

b l e t h e r a g iv e n t h e r b l i g i s p r e s e n t and

how

much t im e i s r e q u i r e d f o r i t , d e ; e n d s upon th e t a s k t h a t i s b e i n g p e r ­ fo rm e d .

I t is also p o s s ib le

to u t i l i z e a le s s d e ta ile d a n a ly s is , o r

e l e m e n t a l m o tio n s c o n f i n e d t o t h e movements o f t h e o p e r a t o r w h ile p e r ­ f o rm in g some t a s k ,

much a n a n a l y s i s n i g h t c o n s i s t o f th e t h e r b l i g s :

t r a n s p o r t em pty, g r a s p , t r a n s p o r t l o a d e d , and a s s e m b l e .

I n su ch an

a n a l y s i s , s e v e r a l " t h e r b l i g s ' ’ would be g ro up ed u n d e r .one h e a d i n g . Hand m o tio n s (5) may be d i v i d e d i n t o f i v e g e n e r a l c l a s s e s : (1) F i n g e r n o t i o n s (2 ) M o tio n s ' i n v o l v i n g fing-mr and w r i s t id ) 1i o t i o n s

i n v o l v i n g f i n g e r , w r i s t , and f o r e a r m •• •

(4) L o t i o n s

i n v o l v i n g f i n n e r , w r i s t , f o r e a r m and u p p e r

aim

(5) I l o t i o n s i n v o l v i n g f i n g e r s , . w r i s t , f o r e a r m , u p p e r a n a and sho o l d e r . T h e se i n t i o n s can be f u r t h e r b ro k e n down i n t o ev en more m in u te

2

d e t a i l , e i t h e r v /ith r e g a r d t o th e m u s c l e s u s e d , o r th e ty p e and w e ig h t o f o b j e c t b e i n g n a n d l e d , t h e d i s t a n c e o v e r w hich th e m o t i on i s u s e d , o r t h e t y p e o f movement ( i . e . s l i d i n g o r c a r r y i n g ) . g r a s p s may be c l a s s i f i e d

F o r e x a m p le " f in g e r

(5) a s :

(1) P r e s s u r e g r a s p , a s i n p i c k i n g u p a p i n l y i n g f l a t on t h e d e sk ." (2; i-. hook g r a s p , when th e f i n g e r s e a n .b e p l a c e d c o m p le te ly a ro u n d th e o b j e c t b e in g p ic k e d u p , o r wnen an o b j e c t i s s l i d o v e r a su rface. I t i s p o s s i b l e t c d e f i n e i n m in u te d e t a i l th e t y p e o f m a n i p u l a t i o n s p e r ­ form ed by an o p e r a t o r on any ty p e o f j o b . ■— ^ t I t was f e l t by t h e i n v e s t i g a t o r t h a t a n a p p r o a c h wh-ich h a s p rov ed so u s e f u l i n p r o m o tin g i n d u s t r i a l e f f i c i e n c y n i g h t be p r o f i t a b l y a p p l i e d t c p s y c h o l o g i c a l p r o b le m s . th a t a ua n ig u l' t i r e

I t seemed l o g i c a l , f o r e x a m p le , t o e x p e c t

t . a t r u s k m ig h t -be a. ulyzc-d i n t o t h e same e l e r s n t s

as an i n d u s t r i a l tu s k ,

hi.-: ,_ntr 1 • .o t i o n e

f t h e t e s t t a s k c o u ld t h e n

be w e ig h te d t o coriu-sgond t o t h e i n d u s t r i a l t a s k .

F o r ex a m p le , f i n g e r

m a n i p u l a t i o n s i n a t o s t i i j . t be i g n o r e d i n t h e s c o r i n g i f t h e y were u n f g p o r t - r b on t h e j o b , w. . i l e f o r e a r m r o v e , a r t s -...ight be g i v e n added im p o r ta n c e i f demandad by vhe j o b . C e r t a i n fu n d a m e n ta l p ro b le m s need t o be s o l v e d b e f o r e i t p o s s ib le to d e t e : r i n e v h e th e r t .is i s a . r a c t i c e l approach.

is (1) Do

i n d i v i d u a l s \ a r y i n t h e t im e r e p a i r e d t o p e r f o r m a g i v e n e l e m e n t a l m o tio n ?

I f t.e re is l i t t l e

v a r i a b i l i ig a: on;; ■ir.e-i v i d u a l s , e l e m e n t a l

r . o t i o n s would n o t be s u i t a b l e f o r s e l e c t i o n o r p r e d i c t i o n .

(2) Y.hat

i s t h e ' r e l a t i o n s h i p b etw een a n i n a i v i d u a l ’ s p e rfo .ir.a n c e on one e l e m e n t a l •m o tio n and h i s p e rfo rm a n c e on a n o t h e r ?

(b) I s t h e tim e f o r t h e whole

o p e r a t i o n r e p r e s e n t a t i v e o f p e r f o r m a n c e on an e l e m e n t a l p a r t o f i t ? t n e e l e m e n t a l n o t i o n s do show -a n i g h d e g r e e o f r e l a t i o n s h i p t o each

If

3

t

o t h e r and t o t h e t o t a l t i n e f o r t h e whole o p e r a t i o n , s u c h an a n a l y s i s would be 'unnecess; r y , ;:.nd t h e t o t a l f i n e f o r t h e w ho le o p e r a t i o n would be t h e b e s t and th e m ost r e p r e s e n t a t i v e s c o r e t o u s e . e l e m e n t a l : o t i o n s a r e in d e p e n d e n t t i

I f , h o w e v e r, t h e s e

u n r e l a t e d , a s i n g l e t a s k c o u ld be

c o n s i d e r e d a s a t e s t b a t t e r y c o n s i s t i n y cl' in d e p e n d e n t u n i t s o f e l e m e n t a l n o tio n s.

dona o f ode t e s t s a v a i l a b l e hav e n o r i ■£ o 'd c h c o n s i d e r e l e m e n t a l

n o t i ojos. P s y c l - c l o y i s t c su c h u s S e a s h o re (8 and u ) , r e n i n

( 7 ) , l .u s ic o (6)

h av e d e m o n s tin te d t h a t t . . e r e i s r o l ; t i v s l y low c o r r e l a t i o n b etw een p e r f o r i .n i c o o o f an i n d i v i d u a l on d i f f e r e n t t- p e s o f m a n i r .u l a t i v e t e s t s . I t would seer, p o s c i :1a t h a t t h e p r e s e n c e o f d i f f e r e n t e l e m e n t a l m o ti o n s , a s w e l l a s d i f f e r a t tim e r e q u i r e m e n t s f o r an e l extent a 1 n o t i o n cornr:on t o two t e s t s , r. i p h t a c c o u n t f o r p a r t o f t h o s e low r e l a t i o n s h i p s *

i ’o r .

enoxtple,- t r a n s p o r t empty and -tc u n s p o r t lo a d e d l u - u i r e more tim e and i n v o l v e d i f f e r e n t m u s c le : r o u p s i n t h e W estern E l e c t r i c I c y B oard a s c o n t r a s t e d w i t h f i e O’ Ccnnei .l.n d h o z t e r i t ; ,

fa st.

P a r t I (P la c in g )

o f th e h i n u a s o t a h a t e o f I a n i p u l a t i o n s r e s t c o n s i s t s p r i m a r i l y o f t r a n s p o r t s e r p t y • nd lo a d e d i n v o l v i n g t h e u s e o f she u p p e r and f o r e a r m . P art II

(T u rn in g ) o f th e same t e s t r e q u i r e s l e s s f o r e a r m t r a n s p o r t tim e

and i r . t r o c u c e s a t r a n s p o r t lo a d e d t y p e o f movement r e q u i r i n g she u s e o f t h e hand

nd f ingex s .

p o s t s such a s t h e iv lin reso ta Assembly P e s t ,

i n v o l v e a wide v a r i e t y o f e l e m e n t a l mot i o n s .

Phe p a t n r n o f movements

for- e a c h o f t h e t ~ s t t a s k s i s , - ^ h e r e r o r e , d i f f e r e n t even when t h e s u b j e c t knows trm. c o r r e c t s o l u t i o n f o r th e t e s t problem s* P ro b le m :

'This s t u d y was d e s i r e d t o i n v e s t i g a t e t h e v a lu e o f

a p p l y i n g n o t i o n a n a l y s i s t o a s t a n d a r d i z e d t a s k w nich would r e q u i r e u n ifo r m t y p e s o f e l e m e n t a l m o tio n s and v.hJ ch c o u la be tim e d a c c u r a t e l v .

4

I t v?£5 l i m i t e d t o t h e n o t i o n a n a l y s i s o f a s im p le ' a s s e m b ly t a s k w h ich r e q u i r e d p r i m a r i l y t h e u s e o f t h e f i n g e r , v / r i s t , and f o r e a r m . a l l y , i t v.as c o n s i d e r e d i m p o r t a n t t o d e t e r m i n e ,

S p e c ific ­

(1) w h e th e r o r n o t t h e r e

a r e i n c i v i d u a l d i f f e r e n c e s i n e l e m e n t a l m o t io n s and t h e e x t e n t o f a n y such v a r i a t i o n s ,

(2) w h e t h e r s p e e d i n p e r f o r m i n g one b a s i c movement c a n

be r e g a r d e d a s i n d i c a t i n g t h e d e g r e e o f p r o f i c i e n c y i n w hich a n o t h e r e l e m e n t a l movement can oe p e r f o r m e d ,

(1) w h e t h e r such an a n a l y s i s s u g g e s t s

f u r t h e r p o s s i b i l i t i e s f o r r e s e a r c h i n th e f i e l d o f a p titu d e t e s t s .

CHAPTx£ I I A fX 'n t i A f t j S

iX .D

X X 1O O x D U - H l f

Jo b A n a ly z e d . The t a s k o f a s s e m b l i n g t e n n u t s on a t h r e a d e d ro d was s e l e c t e d f o r \

a n a ly s is .

(F ig . l )

~

T h is t a s k in v o lv e s p r im a r i l y t h e u se of th e f i n g e r s

f o r t h e a c t u a l a s s e m b ly o f t h e n u t s on a r o d , o f t h e u p p e r and f o r e a r m f o r t h e t r a n s p o r t s , and o f a v / r i s t m o tio n i n s t a r t i n g t h e n u t s on t h e m e t a l rod*

I n t h i s w ay, t h e p r o b le m was n o t c o m p l i c a t e d by com plex

m o tio n s n o r by body m o t i o n s .

A l l t h e p a r t s c o n s i s t e d o f m e t a l , so t h a t

t i m e ' v a l u e s c o u ld e a s i l y be o b t a i n e d w ith t h e t i m e r d e v e l o p e d f o r t h i s research,

r im e v a l u e s c o u ld e a s i l y be o b t a i n e d when t h e t a s k was p e r ­

form ed w i t h e i t h e r t h e p r e f e r r e d hand a l o n e , o r w i t h b o t h h an d s s im u lt­ a n e o u sly .

....

Work P l a c e . The a r r a n g e m e n t ox t h e w ork p l a c e

( F i g . 1) was s t a n d a r d i z e d s o t h a t th e

same t a s k w ould be p e r f o r m e d by e a c h s u b j e c t .

Two t h r e a d e d r o d s , s i x i n c h e s

i n l e n g t h , w e r e p l a c e d i n a m e t a l f i x t u r e im m e d i a t e l y i n f r o n t o f t h e su b ­ je c t.

The r o d s w ere t h r e a d e d f o r a d i s t a n c e o f one i n c h .

ro x im a te ly 1 6 .S th re a d s p e r in c h .

T h e re w ere ap p ­

The r e m i n d e r o f t h e ro d was smooth so

t h a t t h e n u t s c o u ld e a s i l y s l i d e down.

I n o r d e r uiiat i t would .b e u n n e c e s s ­

a r y f o r t h e s u b j e c t t o p u s h t h e n u t o u t o f t h e way and t h u s i n t r o d u c e a n o t h e r m ovem ent, th e r o d was b e n t so t h a t i t made an an l e o f 45 d e g r e e s b o t h from th e work b e n c h and from a l i n e p c r r . e n d i e u l a r t o th e s u b j e c t .

I n t h i s way,

i t was u nn ecessary" f o r t h e s u b j e c t t o a s s i s t i n th e d i s p o s a l o f t h e n u t , and ev en d i f f i c u l t f o r him t o do so i f t h i s were a t t e m p t e d . Two f l a t

.e t a l t r a y s w ere l o c a t e d so t h a t t h e i r f r o n t edge was s e v e n

i n c h e s fro m t h e end o f t h e

th re ad ed ro d .

r e n 3 / 8 —inch, n u t s w ere p l a c e d

F ig u r e 1 . A p p a r a tu s and Y/orlc i l a c e Showing S u b je c t F erfo rm iu g u ask

In each b in .

The d im e n s io n s o f t h e b i n , two by.~six i n c h e s , p r o v id e d

enough s p a c e b e tw e e n t h e n u t s so t h a t t h o s e r e m a in in g w ere n o t d i s t u r b e d . T im in g A p p a r a t u s . One o f t h e f i r s t p r o b le m s WhicH a r o s e i n t h i s i n v e s t i g a t i o n was th e c o s t o f o b t a i n i n g m in u te t im e v a l u e s on a l a r g e number o f s u b j e c t s w i t h an a p p a r a t u s w nicli n e e d n o t be c o n f i n e d t o a l a b o r a t o r y s i t u a t i o n . S t a n d a r d te c i.n iq .u e s (4 ; s u c h a s the u s e o f a s to p w a tc h , m o tio n p i c t u r e s , o r B a r n e s ’ (1; t e c h n i q u e o f u s i n g a c o n s t a n t s p eed p o l y g i a p h and p h o to e le c tric

c e l l s c o u ld h a v e b e e n u s e d .

A now t e c h n i q u e , however-, was

d e v e l o p e d f o r t h i s r e s e a r c h w nich h a s many a d v a n t a g e s o v e r p r e s e n t t e c h n ia u c s.

I t i s n o t o n ly i n e x u e n s i v e , b u t c a n a l s o be u s e d - i n t i m i n g -s.

r a p i d m ovements o f t h e

fin g q rs .

T h is, i s d i f f i c u l t , i f n o t i m p o s s i b le

t o do 7 / i t h o t h e r m e t . i o d s . An a p p a r a t u s * w a s d e s i g n e d w hich was o p e r a t e d d i r e c t l y by th e s u b j e c t when p e r f o r m i n g t h e s t a n m r d i z e d t a s k ,

xhe s u b j e c t was made a p a r t o f an

e l e c t r o n i c c i r c u i t o f low c a p a c i t y , by an e l e c t r o d e a t t a c h e d t o th e w r i s t o f h is u n p r e f e r r e d hand,

l i f e e l e c t r i c a l n a t u r e o f th e c i r c u i t was u n ­

known t o t h e s u b j e c t and i n no way i n t e r f e r e d w i t h h i s p e r f o r m a n c e . d e t a i l s o f . t h i s e le c tr ic ,- . 1 c i r c u i t a r e p r e s e n t e d i n F i g . 2 .

The

The s u b j e c t

c o m p le te d t h e c i r c u i t w h enever he to u c h e d th e r a t e l r o d o r t h e o / 8 - i n c h n u t s w h ich w e re p l a c e d i n t h e b i n s , w* i c h v/ere a l s o w ir e d i n t o t h e c i r ­ c u it.

The s u b j e c t b r o k e t h e c i r c u i t when h i s hands w ere moved fro m t h e

t h r e a d e d r o d aria when a n v t was t a k e n from th e b i n .

T h is e l e c t r o n i c

A

c i r c u i t was u s e d t o a c t i v a t e a n e l e c t r o i n e g n e t i c r e l a y , w hich o p e r a t e d a re c o rd in g pen.

T h i s p en made a r e c o r d on a p a p e r t i c k e r t a p e ( F i g . 3 ) ,

w h ich was moved by a c o u s t a x t s p e e d p o l y g r a p h .

Yi'ken m e a s u re d , t h i s

r e c o r d c o u ld be t r a n s l a t e d d i r e c t l y i n t o tim e v a l u e s .

The d i s t a n c e o f

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r e c o r d w ere t i e

S in c e t h e m a jo r c h a r a c t e r -

some f o r a l l t h e s u b j e c t s , i t was un­

n e c e s s a r y t o n a r k th e r e c o r d a t th e b e g in n in g o f each t r i a l . p re se n te d in F ig . 2 i s ty p ic a l.

The r e c o r d

I t h a s b e e n n a r k e d t o slow t h e d i s ­

t a n c e s w h ic h w ere m e a s u r e d , an d t h e p a r t s o f th e r e c o r d w hich i n d i c a t e t h e t y p e o f movement b e i n g 'p e r f o r m e d .

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fig u re a. Sample P o l y g r a p h H ecord on r a p e o f a Com plete M o tio n C y c l e . ( O n e - t h i r d o r i g i n a l s i z e ) The b e g i n n i n g o f rk e c y c l e i s a t t h e r i g h t a t t h e b e g i n i n g and end o f e a c h e l e m e n t a l n o t i o n c o n t a c t i s made o r b r o k e n . H oto t h a t th e Ag p a r t o f th e r e c o r d shows many make and b r e a k c o n t a c t s r e s u l t i n g fro m th e s e r i e s o f t r a n s p o r t s empty and lo ad ed . E l e m e n t a l M o tio n s I n v e s r i r a t e d . I t rib* o o s s i b l e t o •d e te a m in e th e i n t e r v a l o f t i m e e l a p s i n g when t h e s u b j e c t ’ s hand moved fro m : (1)

The a s s e m b ly f is e c u r e t o t h e b i n w h ic h c o n t a i n e d t h e n u ts.

(2)

The i n t e r v a l o f c o n t a c t with., t h e n u t o r t h e m e t a l b in .

(3)

( T r a n s p o r t em pty o r f . E . )

(G rasp o r G)

The i n t e r v a l be tv/eon r u e c i n a n a t h e f i r s t c o n t a c t w i t h t h e a s s e m b ly f i x t u r e .

(4)

( T r a n s p o r t l o a d e d o r 'f . L. )

The tim e r e q u i r e d f o r g e t t i n g t h e t h r e a d s s t a r t e d on r o d .

10

(Assem bly 1 o r A 1 ) . tn e f i r s t (5)

The

lio te t h a t t h e c i r c u i t i s b r o k e n a f t e r

th re a d i s c o m p le te ly s t a r t e d .

t i m e f o r t u r n i n g t h e n u t down a d i s t a n c e o f one i n c h on t h e t h r e a d e d r o d .

(Assembly 2 o r A 2)

A lth o u g h

t h i s a s s e m b ly i n v o l v e d a s e r i e s o f g r a s p s , u s e , o r t r a n s p o r t s l o a d e d , r e l e a s e s , and t r a n s p o r t s em p ty , t h e t o t a l t i m e f o r t h i s m e n i p u l a t i o n was u s e d . (S)

The t o t a l tim e f o r one co m p lete c y c l e .

P ro ced u re. The s u b j e c t was s t a t e d a t th e w ork b e n c h . ed t o

th e w r i s t o f th e u n _ r e f e r r e d h a n d .'

An e l e c t r o d e was a t t a c h ­

Are r o d and t h e b i n u s e d by

t h e p r e f e r r e d hand w ere w ir e d i i t o .h e ..1 m e t r i c a l c i r c u i t .

The s u b j e c t

was when i n s t r u c t e d a s f o l l o w s : n T l a c o y o u r h a n d s on t h i s f i x t u r e , o r r o d , u n t i l you a r e t o l d t o b e y i n . n u t fro m th o b i n end t u r n i t you c a n ,

Then, a s q u i c k l y a s you c a n , g e t a

down on 't h i s i c d .

Do t . i i s a s ..u ic k ly , a s

b u t do n o t s p i n t h e n u t , s i n c e we a r e i n t o r e s t e d i n how you

do i t w i t h y o u r f i n g e r s . a

ro corc. v/as r a c e v . r e t u u cru e j e c t t u r mci town t e n n u t s w i t h h i s

p r o f e r r ed h a n d ,

a r e s t p e r i o d was i n t r o d u c e d w h i l e tho a p p a r a t u s was

r e a r r a n g e d a s i t nad been a t th e b e g in n in g * The s u b j e c t was t h e n t o l d : do t u i s , u s i n y o o tn .m n d s . Then I s t y , "G c In , a s you c a n .

"hov. I want t o s e e now q u i c k l y yo u can

x_l a c e Dotn ..anus on t n e s e r o d e , l im e t i n s .

;et a n u t i n e a c h i.and and t u r n th em down a s q u i c k l y

T r y t o keep b o t h h an d s d o in g th e same t h i n g .

In case your

l e f t h an d o r r i g h t hand g a t e b e h i n d , k eep y o u r r i g h t h a n d o r l e f t hand on t h i s r o d u n t i l t h e o t h e r hand g e t s c a u g h t u p . t h i s way i n o r d e r t o g e t a r e c o r d . "

I t h a s t o be done

Tne t a p e was m e a s u re d i n m i l l i m e t e r s

11

fo r each t o t a l o p e ra tio n ,

a s w e l l a s f o r e a c h e le m e n t a l mot ion*

t r i a l s wore made f o r b o t h

th e s i n g l e crtL s im u l t a n e o u s two hand p e rfo rm a n c e .

The re c o rd , was x u e r : e n s u r e d i n o r d e r t o fo r e l l o f th e e le m e n ta l m o tio n s.

A se p a ra te

T en

o b t a i n t h e t i l .e v a l u e s r e c o r d s h e e t (I’i g . 4 ) w a s '

u s e d f o r cc :h o f t h e one h u n d re d s u b j e c t s u s e d i n t h e i n v e s t i g a t i o n . The m e d i a n t i c a o f t n e t e n t r i a l s was c o n s i d e r e d t o be t h e su b ­ j e c t 's s c o r e siac-e i t r :; s n o t i n f l u e n c e d by e x tre m e s c o r e s an d gave a p p r o x i m a t e ly t h e same r e s u l t s a s a " s e l e c t e d a v e r a g e " (3) w h ic h a l s o i r . o r e s ex tre m e s c o r e s .

The l e t t e r m ethod i s co: n o n iy u s e d by t i n e

in e a rs

The s u ' j e o t s u se d were c o lle ._ a s h . d e i . t s who . n d l i m i t e d I n d u s t r i a l e ix e ile rc e .

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CHAPTER I I I RiSuU iS T he d a t a , b a s e d u p o n vhe p e r fo r m a n c e o f one h u n d re d s u b j e c t s , w ere a n a l y z e d t o d e t e r m i n e c h a r a c t e r i s t i c s i n t h e p e r f o r m a n c e o f s p e c i f i c e l e m e n t a l m o t io n s and a l s o t o d e t e r m i n e t h e r e l a t i o n s h i p o f p e r f o r m a n c e on d i f f e r e n t e l e m e n t a l n o t i o n s . A v e ra g e t i me va l u e s and r a n ye c f p e r f o r m a n c e . The a v e r a g e * o r mean*and s t a n d a r d d e v i a t i o n o f tio .e s f o r e a c h o f the e l e n E n t a l m o tio n s a r e p r e s e n t e d i n T a b le 1

nd T a b le 2 .

I t w i l l be

n o t i c e d t h a t i n a d d i t i o n t o a m n ge o f m em t i m e s fro m .0 05 1 m i n u t e s t o .1607 m i n u t e s f o r d i f f e r e n t e l e m e n t a l m o t i o n s , t h e r e i s a l s o a d i f f e r e n c e - i n th e d e g r e e t o w h ich i n d i v i d u a l t i m e s c e n t e r a b o u t th e mean * u s shown by t h e r e l a t i v e s i n e o f t h e s t a n d a r d d e v i a t i o n . TABLE 1 THE AVERAGE AED VARIABILITY OS’ TEEFOR.AITCE TILES IE I TAUTES OF StECISTC EUiEKTAL HOT 101-3 IK _:E SIAGLE 'A ID TASK S tan d ard D e v ia t io n

3 D Lean %

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T o t a l C y c le ’‘'E s t i m a t e d d i s t a n c e

14 \

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IJhe l e a s t - d e v i a t i o n a b o u t t h e mean o c c u r s i n g r a s p and t h e g r e a t e s t d e v ia tio n occurs in th e t o t a l t i n e .

T h in i n d i c a t e s t h a t t h e r e a r e

i n d i v i d u a l d i f f e r e n c e s i n t h e q u a l i t y ,o r r a t e , o f p e r f o r m i n g e l e m e n t a l m o tio n s.

E le m e n t a l m o tio n t i m e s , l i k e r e s t q u a n t i t a t i v e m easu res,, a r e

d i s t r i b u t e d a b o v e and below an a v e r a g e s c o r e , w h ich c h a r a c t e r i z e s , t h e p e r fo r m a n c e o f a g ro u p o f i n d i v i d u a l s .

No s p e c i f i c tim e v a l u e , t h e r e ­

f o r e , can be \ised w h ic h would a p p ly t o th e p e r f o r m a n c e o f a l l i n d i v i d u a l s , th e r e is a range o f s c o r e s , r a t h e r th a n a s in g l e s c o r e . 'TABLE 2 THE AVi&AGS I X T Z .m£

V ^-...^IL1T Y OF PLHEOH. AIEE

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T o t a l Cycle

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t line r e q u i r e d f o r e l o m e n t a l m o ti o r s i n t h e s i n g l e and

t h e tv/o handed t a s k . The p e r c e n t a g e i n c r e a s e i n th e t im e r e q u i r e d f o r t h e same e l e m e n t a l m o tio n s i n t h e two h an d ed t a s k a s com pared t o t h e s i n g l e h a n d e d t a s k i s o r e s e a t e d i n T able 3 .

15

TABLE 3

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