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Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
11
Prin
cipl
es &
Ben
efits
of U
ser
Cen
tere
d U
ser
Inte
rfac
e D
esig
nP
rinci
ples
& B
enef
its o
f Use
r C
ente
red
Use
r In
terf
ace
Des
ign
Jim
W. B
erne
yJi
m W
. Ber
ney
Usa
bili
ty M
anag
emen
t, In
c.U
sab
ility
Man
agem
ent,
Inc.
jim.b
ern
ey@
usa
bilit
y.co
mjim
.ber
ney
@u
sabi
lity.
com
Apr
il 26
, 199
8A
pril
26, 1
998
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
22
Com
mon
Mis
conc
eptio
nsC
omm
on M
isco
ncep
tions
U
sers
do
nU
sers
do
n ’’ t k
no
w w
hat
they
wan
tt k
no
w w
hat
they
wan
t
W
e d
on
We
do
n ’’t h
ave
the
time
to c
on
sult
our
use
rst h
ave
the
time
to c
on
sult
our
use
rs
W
e h
ave
too
man
y u
sers
, can
We
hav
e to
o m
any
use
rs, c
an ’’ t ta
lk to
them
all
t tal
k to
them
all
W
e kn
ow
wh
at o
ur
use
rs w
ant
We
kno
w w
hat
ou
r u
sers
wan
t
W
e w
ill d
esig
n it
rig
ht th
e fir
st ti
me
We
will
des
ign
it r
ight
the
first
tim
e
don
don ’’
t acc
ept t
hat d
esig
n is
iter
ativ
et a
ccep
t tha
t des
ign
is it
erat
ive
m
ust i
nclu
de ti
me
to te
st &
deb
ug U
Im
ust i
nclu
de ti
me
to te
st &
deb
ug U
I
N
o p
rob
lem
, th
e u
sers
will
be
trai
ned
!N
o p
rob
lem
, th
e u
sers
will
be
trai
ned
!
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
33
Com
mon
Des
ign
Pro
blem
sC
omm
on D
esig
n P
robl
ems
C
om
mun
icat
ions
gap
bet
wee
n us
ers
and
deve
lope
rs
Co
mm
unic
atio
ns g
ap b
etw
een
user
s an
d de
velo
pers
N
o m
etho
dolo
gy fo
r U
I des
ign
No
met
hodo
logy
for
UI d
esig
n
D
evel
oper
s la
ck G
UI d
esig
n ex
perie
nce
Dev
elop
ers
lack
GU
I des
ign
expe
rienc
e
N
o us
abili
ty o
bjec
tives
or
targ
et m
easu
res
No
usab
ility
obj
ectiv
es o
r ta
rget
mea
sure
s
N
o tim
e fo
r ite
rativ
e de
sign
and
usa
bilit
y te
stin
gN
o tim
e fo
r ite
rativ
e de
sign
and
usa
bilit
y te
stin
g
R
eal u
sers
are
not
ava
ilabl
e fo
r us
abili
ty te
stin
gR
eal u
sers
are
not
ava
ilabl
e fo
r us
abili
ty te
stin
g
U
sabi
lity
test
ing
is p
erfo
rmed
too
late
...U
sabi
lity
test
ing
is p
erfo
rmed
too
late
...
onl
y tim
e fo
r m
ino
r im
pro
vem
ents
onl
y tim
e fo
r m
ino
r im
pro
vem
ents
n
o tim
e to
fix
con
cep
tual
des
ign
pro
blem
s.n
o tim
e to
fix
con
cep
tual
des
ign
pro
blem
s.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
44
Com
mon
Usa
bilit
y P
robl
ems
Com
mon
Usa
bilit
y P
robl
ems
D
iffic
ult t
o us
e (t
erm
inol
ogy,
unc
lear
nav
igat
ion,
la
ck o
f D
iffic
ult t
o us
e (t
erm
inol
ogy,
unc
lear
nav
igat
ion,
la
ck o
f co
nsis
tenc
y, p
oor
feed
back
, int
oler
ant t
o er
ror)
cons
iste
ncy,
poo
r fe
edba
ck, i
ntol
eran
t to
erro
r)
C
once
ptua
l des
ign
prob
lem
sC
once
ptua
l des
ign
prob
lem
s
D
oesn
Doe
sn’’ t
mee
t use
r ne
eds
(poo
r ta
sk a
naly
sis)
t mee
t use
r ne
eds
(poo
r ta
sk a
naly
sis)
D
oesn
Doe
sn’’ t
pro
vide
the
need
ed in
form
atio
nt p
rovi
de th
e ne
eded
info
rmat
ion
R
equi
res
the
user
to r
emem
ber
too
muc
h in
form
atio
n R
equi
res
the
user
to r
emem
ber
too
muc
h in
form
atio
n (c
odes
, ter
min
olog
y)
(cod
es, t
erm
inol
ogy)
D
oesn
Doe
sn’’ t
dis
play
info
rmat
ion
in a
use
ful o
r na
tura
l for
mat
t d
ispl
ay in
form
atio
n in
a u
sefu
l or
natu
ral f
orm
at
(out
side
use
r(o
utsi
de u
ser ’’ s
kno
wle
dge
and
task
dom
ain)
s kn
owle
dge
and
task
dom
ain)
P
rodu
ct la
cks
visu
al a
ppea
l (P
rodu
ct la
cks
visu
al a
ppea
l ( ““ out
of t
he b
ox e
xper
ienc
eou
t of t
he b
ox e
xper
ienc
e ”” ) )
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
55
Inte
rest
ing
Sta
tistic
s -
Sal
es/M
arke
ting
Inte
rest
ing
Sta
tistic
s -
Sal
es/M
arke
ting
40
% o
f buy
ers
look
at a
ltern
ativ
e pr
oduc
ts b
ecau
se
the
40%
of b
uyer
s lo
ok a
t alte
rnat
ive
prod
ucts
bec
ause
th
e in
stal
led
syst
em d
oes
not m
eet t
heir
nee
ds.
52%
of
in
stal
led
syst
em d
oes
not m
eet t
heir
nee
ds.
52%
of
re
spon
dent
s ci
ted
perf
orm
ance
and
eas
ere
spon
dent
s ci
ted
perf
orm
ance
and
eas
e-- o
fof
-- use
as
the
use
as th
e m
ajor
fact
or in
fluen
cing
a p
urch
ase
maj
or fa
ctor
influ
enci
ng a
pur
chas
e (D
ata
Dec
isio
ns
(Dat
a D
ecis
ions
A
pplic
atio
ns
So
ftwar
e S
urve
y, 1
985)
App
licat
ion
s S
oftw
are
Sur
vey,
198
5)
M
arke
ting
Mar
ketin
g --
focu
s on
usa
bilit
y &
cus
tom
er s
atis
fact
ion
focu
s on
usa
bilit
y &
cus
tom
er s
atis
fact
ion
A
vera
ge o
f 11.
2 us
abili
ty r
elat
ed c
omm
ents
fou
nd p
er
Ave
rage
of 1
1.2
usab
ility
rel
ated
com
men
ts fo
und
pe
r m
agaz
ine
revi
ew a
rtic
le
mag
azin
e re
view
art
icle
(A
nd
erso
n, 1
990)
(An
der
son
, 199
0)
In
foW
orld
ass
igns
18
Info
Wor
ld a
ssig
ns 1
8 -- 30%
of s
oftw
are
rev
iew
art
icle
s 30
% o
f sof
twa
re r
evie
w a
rtic
les
to 1
) E
ase
of L
earn
ing;
2)
Eas
e of
Use
; 3)
Qua
lity
of
to 1
) E
ase
of L
earn
ing;
2)
Eas
e of
Use
; 3)
Qua
lity
of
docu
men
tatio
n.do
cum
enta
tion.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
66
Inte
rest
ing
Sta
tistic
s -
Dev
elop
men
tIn
tere
stin
g S
tatis
tics
-D
evel
opm
ent
U
I = 4
7U
I = 4
7 --60
% o
f app
licat
ion
code
60
% o
f app
licat
ion
code
(M
acIn
tyre
, E
step
, S
iebu
rth
(M
acIn
tyre
, E
step
, S
iebu
rth
1
990
)1
990
)
U
I = 2
9% o
f dev
elop
men
t bud
get
UI =
29%
of d
evel
opm
ent b
udge
t (R
ose
nbe
rg, 1
989)
(Ro
sen
berg
, 198
9)
C
ost o
f cha
nge
Cos
t of c
hang
e (Pre
ssm
an, 1
992
)(P
ress
man
, 199
2)
d
urin
g p
roje
ct d
efin
itio
n d
urin
g p
roje
ct d
efin
itio
n --1
unit
1 un
it
d
urin
g d
evel
opm
ent
dur
ing
dev
elop
men
t --1.
51.
5 --6
un
its6
un
its
d
urin
g m
ain
tena
nce
d
urin
g m
ain
tena
nce
--
6060-- 1
00
uni
ts10
0 u
nits
A
mer
ican
Airl
ines
foun
d th
at id
entif
ying
and
fixi
ng A
mer
ican
Airl
ines
foun
d th
at id
entif
ying
and
fixi
ng us
abili
ty p
robl
ems
duri
ng d
esig
n sa
ved
60us
abili
ty p
robl
ems
duri
ng d
esig
n sa
ved
60 -- 90%
. 90
%. (
LaP
lan
te,
(LaP
lan
te,
199
2)
199
2)
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
77
Inte
rest
ing
Sta
tistic
s -
Dev
elop
men
tIn
tere
stin
g S
tatis
tics
-D
evel
opm
ent
63
% o
f sof
twar
e pr
ojec
ts e
xcee
d es
timat
es
63%
of s
oftw
are
proj
ects
exc
eed
estim
ates
(L
eder
er a
nd
(Led
erer
and
P
rass
ad, 1
992
)P
rass
ad, 1
992
)
1
) us
er c
han
ge
req
ues
ts; 2
) ov
erlo
oked
task
s; 3
) u
sers
do
n1
) us
er c
han
ge
req
ues
ts; 2
) ov
erlo
oked
task
s; 3
) u
sers
do
n ’’t t
und
erst
and
thei
r o
wn
req
uire
men
ts; 4
) po
or c
om
mu
nic
atio
n
und
erst
and
thei
r o
wn
req
uire
men
ts; 4
) po
or c
om
mu
nic
atio
n
bet
wee
n u
ser/
anal
yst
bet
wee
n u
ser/
anal
yst
E
urop
ean
Com
mun
ity (
EC
) st
anda
rds
dire
ctiv
e re
quir
e:
Eur
opea
n C
omm
unity
(E
C)
stan
dard
s di
rect
ive
requ
ire
:
““ sof
twar
e m
ust
be
easy
to u
seso
ftwar
e m
ust
be
easy
to u
se ””
““ s
oftw
are
mu
st b
e su
itab
le fo
r th
e ta
skso
ftwar
e m
ust
be
suita
ble
for
the
task
””
““ p
rinci
ple
s of
so
ftwar
e er
gon
omic
s m
ust
be
appl
ied
prin
cip
les
of s
oftw
are
erg
onom
ics
mu
st b
e ap
plie
d””
C
om
pani
es lo
se 3
3% o
f afte
rC
om
pani
es lo
se 3
3% o
f afte
r-- t
ax p
rofit
whe
n th
ey s
hip
6 ta
x pr
ofit
whe
n th
ey s
hip
6 m
onth
s la
te v
s. 3
.5%
wh
en th
ey e
xcee
d de
velo
pmen
t m
onth
s la
te v
s. 3
.5%
wh
en th
ey e
xcee
d de
velo
pmen
t bu
dget
s by
50%
.bu
dget
s by
50%
.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
88
Inte
rest
ing
Sta
tistic
s -
Ong
oing
Mai
nten
ance
Inte
rest
ing
Sta
tistic
s -
Ong
oing
Mai
nten
ance
8
0%
of l
ifecy
cle
cost
s o
ccu
r in
mai
nte
nan
ce
80
% o
f life
cycl
e co
sts
occ
ur
in m
ain
ten
ance
(P
ress
man
, 19
92
)(P
ress
man
, 19
92
)
8
0%
of
mai
nte
nan
ce is
cau
sed
by
un
met
or
80
% o
f m
ain
ten
ance
is c
ause
d b
y u
nm
et o
r u
nfo
rese
en u
ser
req
uire
men
ts, 2
0%
is c
ause
d b
y u
nfo
rese
en u
ser
req
uire
men
ts, 2
0%
is c
ause
d b
y b
ug
s o
r re
liab
ility
pro
ble
ms
(Mar
tin, M
cClu
re,
bu
gs
or
relia
bili
ty p
rob
lem
s (M
artin
, McC
lure
, 1
98
3)
19
83
)
H
elp
des
k su
ppo
rt c
alls
co
st b
etw
een
$1
2 a
nd
H
elp
des
k su
ppo
rt c
alls
co
st b
etw
een
$1
2 a
nd
$
25
0/ca
ll.$
25
0/ca
ll.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
99
How
a U
ser
Gro
up B
enef
its fr
om
Usa
bilit
y E
ngin
eerin
gH
ow a
Use
r G
roup
Ben
efits
from
U
sabi
lity
Eng
inee
ring
In
crea
sed
prod
uctiv
ity (
help
s st
abili
ze o
r lo
wer
st
aff c
ost)
Incr
ease
d pr
oduc
tivity
(he
lps
stab
ilize
or
low
er s
taf
f cos
t)
P
rodu
ct b
ette
r m
eets
use
r go
als,
task
s, a
nd o
bjec
tive
sP
rodu
ct b
ette
r m
eets
use
r go
als,
task
s, a
nd o
bjec
tive
s
B
ette
r pr
oduc
t usa
bilit
yB
ette
r pr
oduc
t usa
bilit
y
D
ecre
ased
use
r er
rors
Dec
reas
ed u
ser
erro
rs
D
ecre
ased
trai
ning
cos
tsD
ecre
ased
trai
ning
cos
ts
D
ecre
ased
use
r su
ppor
t (he
lp d
esk,
bud
dy, s
uper
viso
r,
Dec
reas
ed u
ser
supp
ort (
help
des
k, b
uddy
, sup
ervi
sor,
do
cum
enta
tion)
docu
men
tatio
n)
S
hort
er in
terv
als
(lead
tim
e) fo
r ne
w fu
nctio
nalit
yS
hort
er in
terv
als
(lead
tim
e) fo
r ne
w fu
nctio
nalit
y
B
ette
r us
er s
atis
fact
ion
Bet
ter
user
sat
isfa
ctio
n --P
ossi
ble
redu
ctio
n in
em
ploy
ee
Pos
sibl
e re
duct
ion
in e
mpl
oyee
tu
rnov
ertu
rnov
er
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1010
How
a V
endo
r B
enef
its fr
om
Usa
bilit
y E
ngin
eerin
gH
ow a
Ven
dor
Ben
efits
from
U
sabi
lity
Eng
inee
ring
In
crea
sed
sale
s (s
atis
fact
ion,
mar
ket a
ppea
l, us
abi
lity
as a
In
crea
sed
sale
s (s
atis
fact
ion,
mar
ket a
ppea
l, us
abi
lity
as a
fe
atur
e)
feat
ure)
--R
equi
red
if co
mpe
titor
Req
uire
d if
com
petit
or ’’s
focu
s is
usa
bilit
y!s
focu
s is
usa
bilit
y!
use
rs d
ecid
e if
a pr
odu
ct is
usa
ble
in le
ss th
an 1
hou
ru
sers
dec
ide
if a
pro
duct
is u
sab
le in
less
than
1 h
our
u
sers
rat
ed e
ase
use
rs r
ated
eas
e-- o
fo
f --u
se s
eco
nd a
t 6.8
ou
t of 1
0 an
d e
ase
use
sec
ond
at 6
.8 o
ut o
f 10
and
eas
e-- o
fof
-- lea
rnin
g
lear
nin
g
four
th a
t 6.4
.fo
urth
at 6
.4.
R
educ
ed c
ost t
o id
entif
y an
d pr
iorit
ize
requ
irem
ent
sR
educ
ed c
ost t
o id
entif
y an
d pr
iorit
ize
requ
irem
ent
s
R
educ
ed c
ost o
f dev
elop
men
t R
educ
ed c
ost o
f dev
elop
men
t --
mak
e ch
ange
s ea
rly
mak
e ch
ange
s ea
rly
M
inim
ize
last
min
ute
chan
ges
to p
ublic
atio
ns a
nd tr
aini
ngM
inim
ize
last
min
ute
chan
ges
to p
ublic
atio
ns a
nd tr
aini
ng
D
ecre
ased
cus
tom
er s
uppo
rt (
hot
Dec
reas
ed c
usto
mer
sup
port
(ho
t-- lin
e ca
ll vo
lum
e)lin
e ca
ll vo
lum
e)
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1111
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
durin
g th
e P
lann
ing
Pha
se?
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
durin
g th
e P
lann
ing
Pha
se?
Id
entif
y Id
entif
y U
ser
Pro
file
Use
r P
rofil
e --cu
stom
er s
ite v
isits
, int
ervi
ews,
use
r cu
stom
er s
ite v
isits
, int
ervi
ews,
use
r su
rvey
s, fo
cus
grou
pssu
rvey
s, fo
cus
grou
ps
P
erfo
rm
Per
form
Co
mpe
titiv
e A
naly
sis
Co
mpe
titiv
e A
naly
sis --
eval
uate
usa
bilit
y of
ev
alua
te u
sabi
lity
of
com
petin
g pr
oduc
ts (
wha
t wor
ks?
wha
t doe
snco
mpe
ting
prod
ucts
(w
hat w
orks
? w
hat d
oesn
’’ t?
wha
t t?
wha
t ne
eds
impr
ovin
g? H
ow d
o us
ers
use
your
com
petit
orne
eds
impr
ovin
g? H
ow d
o us
ers
use
your
com
petit
or’’ s
s pr
oduc
t?).
Res
ults
can
be
inpu
t int
o us
abili
ty o
bjec
tive
prod
uct?
). R
esul
ts c
an b
e in
put i
nto
usab
ility
obj
ectiv
e m
easu
res.
m
easu
res.
P
erfo
rm
Per
form
Ne
eds
Ass
essm
ent
Ne
eds
Ass
essm
ent
--W
hat a
re c
usto
mer
nee
ds?
W
hat a
re c
usto
mer
nee
ds?
A
re c
usto
mer
nee
ds c
urre
ntly
bei
ng m
et.
Are
cus
tom
er n
eeds
cur
rent
ly b
eing
met
.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1212
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
durin
g th
e P
lann
ing
Pha
se?
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
durin
g th
e P
lann
ing
Pha
se?
C
ritic
al
Crit
ical
Inci
dent
Ana
lysi
s In
cide
nt A
naly
sis --
iden
tify
usab
ility
pro
blem
s th
at
iden
tify
usab
ility
pro
blem
s th
at
gene
rate
cal
ls to
the
supp
ort l
ine
and/
or le
ad to
mis
use
or
gene
rate
cal
ls to
the
supp
ort l
ine
and/
or le
ad to
mis
use
or
over
use.
Goa
l is
to s
top
first
cal
l, an
d th
us p
oss
ible
rep
eat
over
use.
Goa
l is
to s
top
first
cal
l, an
d th
us p
oss
ible
rep
eat
calle
rs.
Use
ser
vice
and
mai
nten
ance
rec
ords
and
cus
tom
er
calle
rs.
Use
ser
vice
and
mai
nten
ance
rec
ords
and
cus
tom
er
com
plai
nts.
com
plai
nts.
S
et
Set
usa
bilit
y ob
ject
ives
and
mea
sure
s us
abili
ty o
bjec
tives
and
mea
sure
s (n
eed
basi
s an
d (n
eed
basi
s an
d co
mpa
rativ
e da
ta fr
om s
imila
r pr
oduc
ts)
com
para
tive
data
from
sim
ilar
prod
ucts
)
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1313
Usa
bilit
y E
ngin
eerin
g -
Pla
nnin
g P
hase
Bui
ld a
Use
r (G
roup
) P
rofil
eU
sabi
lity
Eng
inee
ring
-P
lann
ing
Pha
seB
uild
a U
ser
(Gro
up)
Pro
file
K
now
thy
Use
r!
Kno
w th
y U
ser!
--N
o su
bstit
ute
for
the
real
use
r.N
o su
bstit
ute
for
the
real
use
r.
G
athe
r ba
ckgr
ound
info
rmat
ion
abou
t you
r us
ers.
Gat
her
back
grou
nd in
form
atio
n ab
out y
our
user
s.
Psy
chol
ogic
al:
attit
ude
, mot
iva
tion
Psy
chol
ogic
al:
attit
ude
, mot
iva
tion
E
xpe
rienc
e a
nd fu
ture
use
(no
vice
, adv
anc
ed)
Exp
erie
nce
and
futu
re u
se (
novi
ce, a
dva
nce
d)
Jo
b ta
sk, e
duca
tion
(dom
ain
kno
wle
dge
)Jo
b ta
sk, e
duca
tion
(dom
ain
kno
wle
dge
)
P
hysi
cal a
spe
cts
of u
ser,
of
wor
kpla
ceP
hysi
cal a
spe
cts
of u
ser,
of
wor
kpla
ce
A
sses
s ho
w u
ser
back
grou
nd im
pact
s us
er p
erfo
rman
ce,
Ass
ess
how
use
r ba
ckgr
ound
impa
cts
user
per
form
ance
, ob
ject
ives
, tas
k ex
ecut
ion,
inte
rpre
tatio
n.ob
ject
ives
, tas
k ex
ecut
ion,
inte
rpre
tatio
n.
Id
entif
y P
rimar
y an
d S
econ
dary
use
r gr
oups
Iden
tify
Prim
ary
and
Sec
onda
ry u
ser
grou
ps
Exp
ert
mod
e a
nd s
hort
Exp
ert
mod
e a
nd s
hort -- cut
s, s
epa
rate
inte
rfac
es
for
the
sam
e ta
skcu
ts, s
epa
rate
inte
rfac
es
for
the
sam
e ta
sk
S
houl
d tr
aini
ng ta
rge
t ea
se o
f le
arn
ing
or e
ase
of
use?
Sho
uld
trai
ning
targ
et e
ase
of l
ea
rnin
g or
ea
se o
f us
e?
H
elp
sho
uld
targ
et
use
r pr
ofile
s (t
ask
and
ope
ratio
nal h
elp
)H
elp
sho
uld
targ
et
use
r pr
ofile
s (t
ask
and
ope
ratio
nal h
elp
)
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1414
Usa
bilit
y E
ngin
eerin
g -
Pla
nnin
g P
hase
Set
Usa
bilit
y G
oals
Usa
bilit
y E
ngin
eerin
g -
Pla
nnin
g P
hase
Set
Usa
bilit
y G
oals
D
efin
e an
d q
uan
tify
ob
ject
ives
for
usa
bili
ty,
Def
ine
and
qu
antif
y o
bje
ctiv
es fo
r u
sab
ility
, ac
cep
tab
ility
, per
form
ance
, an
d fu
nct
iona
lity.
acce
pta
bili
ty, p
erfo
rman
ce, a
nd
fun
ctio
nalit
y.
E
very
pro
du
ct m
ust
hav
e U
sab
ility
Go
als
Eve
ry p
rod
uct
mu
st h
ave
Usa
bili
ty G
oal
s --
def
ine
def
ine
early
early
S
ho
uld
sup
po
rt P
rodu
ct G
oal
sS
ho
uld
sup
po
rt P
rodu
ct G
oal
s
G
oal
s ca
n b
e G
oal
s ca
n b
e ““hi
gh
leve
lhi
gh
leve
l ””in
itial
ly, b
ut b
eco
me
initi
ally
, bu
t bec
om
e m
ore
det
aile
d a
s yo
ur
pro
du
ct m
atu
res.
mo
re d
etai
led
as
you
r p
rod
uct
mat
ure
s.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1515
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
in th
e A
naly
sis
Pha
se?
How
can
Usa
bilit
y E
ngin
eerin
g H
elp
in th
e A
naly
sis
Pha
se?
E
arly
and
con
tinua
l foc
us o
n us
ers
& ta
sks
Ear
ly a
nd c
ontin
ual f
ocus
on
user
s &
task
s --
Par
ticip
ator
y,
Par
ticip
ator
y,
inte
ract
ive
team
des
ign
inte
ract
ive
team
des
ign
E
valu
ate
Usa
bilit
y ea
rly a
nd o
ften
Eva
luat
e U
sabi
lity
early
and
ofte
n --do
it w
hen
itdo
it w
hen
it ’’s
chea
p.
s ch
eap.
A
vera
ge u
sabi
lity
test
iden
tifie
s 70
Ave
rage
usa
bilit
y te
st id
entif
ies
70 -- 100
des
ign
issu
es (
Jeff
100
desi
gn is
sues
(Je
ff S
chue
ler,
199
2)
Sch
uele
r, 1
992)
Ite
rativ
e de
sign
, tes
t for
usa
bilit
y, a
nd r
edes
ign
Itera
tive
desi
gn, t
est f
or u
sabi
lity,
and
red
esig
n
E
nsur
e a
Use
r dr
iven
vs.
Pro
cess
, Dat
a, o
r T
echn
olo
gy
Ens
ure
a U
ser
driv
en v
s. P
roce
ss, D
ata,
or
Tec
hnol
ogy
dr
iven
des
ign
driv
en d
esig
n
S
tand
ards
for
GU
I des
ign
(Ind
ustr
y &
com
pany
)S
tand
ards
for
GU
I des
ign
(Ind
ustr
y &
com
pany
)
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1616
Typ
ical
UI D
esig
n M
etho
dolo
gyT
ypic
al U
I Des
ign
Met
hodo
logy
A
ssem
ble
des
ign
team
with
crit
ical
ski
lls
Ass
emb
le d
esig
n te
am w
ith c
ritic
al s
kills
D
efin
e D
efin
e ““ h
igh
leve
l tas
k flo
wh
igh
leve
l tas
k flo
w ””
S
elec
t UI
pla
tfo
rm, G
UI d
evel
op
men
t to
ols
Sel
ect U
I p
latf
orm
, GU
I dev
elo
pm
ent t
oo
ls
D
efin
e D
efin
e ““ d
etai
led
task
flo
wd
etai
led
task
flo
w ””
D
evel
op
low
fid
elity
win
do
w p
roto
typ
esD
evel
op
low
fid
elity
win
do
w p
roto
typ
es
D
evel
op
Ap
plic
atio
n U
I H
and
bo
ok
Dev
elo
p A
pp
licat
ion
UI
Han
db
oo
k
P
erfo
rm In
form
al u
sab
ility
test
ing
Per
form
Info
rmal
usa
bili
ty te
stin
g
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1717
Typ
ical
UI D
esig
n M
etho
dolo
gyT
ypic
al U
I Des
ign
Met
hodo
logy
D
ocu
men
t UI
req
uire
men
tsD
ocu
men
t UI
req
uire
men
ts
D
evel
op
Usa
bili
ty T
est
Sce
nar
ios
Dev
elo
p U
sab
ility
Te
st S
cen
ario
s
D
evel
op
Usa
bili
ty T
est
Pla
n &
Sch
edu
leD
evel
op
Usa
bili
ty T
est
Pla
n &
Sch
edu
le
D
evel
op
a N
avig
atio
nal
pro
toty
pe
Dev
elo
p a
Nav
igat
ion
al p
roto
typ
e
P
erfo
rm F
orm
al U
sab
ility
Tes
ting
Per
form
Fo
rmal
Usa
bili
ty T
estin
g
D
evel
op
Fin
al P
roto
typ
e D
evel
op
Fin
al P
roto
typ
e --re
fine
req
uire
men
tsre
fine
req
uire
men
ts
B
uild
Bu
ild
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1818
Ski
lls R
equi
red
on th
e U
I Des
ign
Tea
mS
kills
Req
uire
d on
the
UI D
esig
n T
eam
Interface Design
Stu
dy
use
rs’
task
s an
den
vir
on
men
tB
uil
d t
he
anal
ysi
s d
eliv
erab
les
and
win
do
ws
Human Factors
Ass
ist
wit
h c
og
nit
ive
psy
cho
log
yas
pec
ts o
f G
UI
Ass
ist
wit
h u
sab
ilit
y t
esti
ng
Graphic Design
Hel
p i
n d
esig
nin
g I
con
s fo
r o
bje
cts
Ass
ist
in w
ind
ow
aes
thet
icTechnical Writing
Ass
ist
wit
h H
elp
fa
cili
tyU
ser
Ref
eren
ce g
uid
es
Data M
odeling/
Domain Object M
odeling
Ass
ist
wit
h i
den
tify
ing
ob
ject
s, a
ctio
ns
and
attr
ibu
tes
Business Expertise
Sp
ecif
y b
usi
nes
sre
qu
irem
ents
Ass
ist
crea
tin
gG
UI
win
do
ws
Training Expertise
Des
ign
ap
pro
pri
ate
trai
nin
gco
mp
on
ents
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
1919
10 C
ompo
nent
s of
a U
sabl
e D
esig
n10
Com
pone
nts
of a
Usa
ble
Des
ign
T
ask
Des
ign
that
T
ask
Des
ign
that
su
ppo
rts
the
use
rsu
ppo
rts
the
use
r
D
esig
n th
at s
up
port
s D
esig
n th
at s
up
port
s d
evel
opm
en
t of t
he
dev
elop
me
nt o
f th
e u
ser
use
r ’’ s M
enta
l Mo
del
s M
enta
l Mo
del
B
uild
a M
etap
ho
r to
B
uild
a M
etap
ho
r to
en
han
ce le
arn
ing
enh
ance
lear
nin
g
C
on
sist
ency
Co
nsi
sten
cy
A
vaila
bili
tyA
vaila
bili
ty
F
eed
bac
kF
eed
bac
k
E
rro
r H
and
ling
Err
or
Han
dlin
g
P
ut t
he
use
r in
Co
ntr
ol
Pu
t th
e u
ser
in C
on
tro
l
D
esig
n fo
r h
um
an
Des
ign
for
hu
man
lim
itatio
ns
and
lim
itatio
ns
and
p
erfo
rman
cep
erfo
rman
ce
P
rovi
de
effe
ctiv
e P
rovi
de
effe
ctiv
e g
rap
hic
s an
d a
rt.
gra
ph
ics
and
art
.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2020
Effe
ctiv
e T
ask
Des
ign
Effe
ctiv
e T
ask
Des
ign
T
ask
desi
gn
mu
st m
atch
:T
ask
desi
gn
mu
st m
atch
:
actu
al u
se a
nd
job
req
uire
men
tsac
tual
use
an
d jo
b r
equ
irem
ents
u
ser
use
r ’’ s m
enta
l mo
del
s m
enta
l mo
del
u
ser
use
r ’’ s o
bje
ctiv
ess
ob
ject
ives
T
ask
desi
gn
mu
st b
e fle
xib
le:
Tas
k de
sig
n m
ust
be
flexi
ble
:
exte
nd
func
tion
ality
an
d u
sag
e sc
enar
ios
exte
nd
func
tion
ality
an
d u
sag
e sc
enar
ios
ad
d n
ew c
apab
ility
add
new
cap
abili
ty
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2121
Bui
ldin
g th
e U
ser’s
Men
tal M
odel
Bui
ldin
g th
e U
ser’s
Men
tal M
odel
U
ser
Use
r ’’ s k
now
ledg
e of
how
a s
yste
m w
orks
(e.
g., i
nput
s /
s kn
owle
dge
of h
ow a
sys
tem
wor
ks (
e.g.
, inp
uts
/ ou
tput
s, in
visi
ble
as w
ell a
s vi
sibl
e pr
oces
ses,
ho
w a
nd
outp
uts,
invi
sibl
e as
wel
l as
visi
ble
proc
esse
s, h
ow
and
w
hy it
wor
ks, n
avig
atio
n, a
nd s
truc
ture
)w
hy it
wor
ks, n
avig
atio
n, a
nd s
truc
ture
)
M
enta
l Mo
del
s o
ften
are
:M
enta
l Mo
del
s o
ften
are
:
Inco
mpl
ete,
inco
nsis
tent
, im
prec
isel
y de
fined
Inco
mpl
ete,
inco
nsis
tent
, im
prec
isel
y de
fined
C
onfu
sed
with
sim
ilar
syst
ems
Con
fuse
d w
ith s
imila
r sy
stem
s
W
hy
both
er w
ith m
enta
l mo
dels
?W
hy
both
er w
ith m
enta
l mo
dels
?
Allo
ws
the
desi
gner
to le
arn
busi
ness
req
uire
men
ts;
A
llow
s th
e de
sign
er to
lear
n bu
sine
ss r
equi
rem
ents
;
initi
al s
tep
in p
erfo
rmin
g ta
sk a
naly
sis
initi
al s
tep
in p
erfo
rmin
g ta
sk a
naly
sis
C
apita
lize
on w
hat t
he u
ser
alre
ady
know
sC
apita
lize
on w
hat t
he u
ser
alre
ady
know
s
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2222
Usi
ng a
Met
aph
or in
You
r D
esig
nU
sing
a M
eta
phor
in Y
our
Des
ign
S
imp
lifie
s co
mpl
ex ta
sks
Sim
plif
ies
com
plex
task
s
T
akes
adv
anta
ge
of e
xist
ing
use
r kn
ow
ledg
eT
akes
adv
anta
ge
of e
xist
ing
use
r kn
ow
ledg
e
D
onD
on’’ t
forc
e a
met
apho
r t f
orc
e a
met
apho
r --no
t a r
equ
irem
ent
not a
req
uire
men
t
T
ask
obje
cts
and
hie
rarc
hy m
ay b
e am
ple
T
ask
obje
cts
and
hie
rarc
hy m
ay b
e am
ple
m
etap
hor
met
aph
or
D
onD
on’’ t
let t
he
met
apho
r ob
stru
ct w
ith u
ser
t let
the
met
apho
r ob
stru
ct w
ith u
ser
ban
dwid
th (
abili
ty to
com
ple
te th
e ta
sk).
ban
dwid
th (
abili
ty to
com
ple
te th
e ta
sk).
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2323
UI C
onsi
sten
cyU
I Con
sist
ency
In
tern
al (
con
trol
s, la
you
t, te
rmin
olo
gy,
dra
g a
nd
In
tern
al (
con
trol
s, la
you
t, te
rmin
olo
gy,
dra
g a
nd
d
rop
, ob
ject
sel
ectio
n, o
bje
ct m
anip
ula
tion
)d
rop
, ob
ject
sel
ectio
n, o
bje
ct m
anip
ula
tion
)
E
xter
nal
(st
yle
gui
des
, oth
er in
dust
ry a
pplic
atio
ns)
Ext
ern
al (
styl
e g
uid
es, o
ther
indu
stry
app
licat
ions
)
N
avig
atio
n (
men
u d
esig
n, m
ove
men
t bet
wee
n
Nav
igat
ion
(m
enu
des
ign
, mo
vem
ent b
etw
een
w
ind
ow
s, m
ove
men
t bet
wee
n f
ield
s)w
ind
ow
s, m
ove
men
t bet
wee
n f
ield
s)
T
ask
des
ign
Tas
k d
esig
n
R
equ
ired
for
incr
eme
nta
l lea
rnin
gR
equ
ired
for
incr
eme
nta
l lea
rnin
g
A
pp
le S
tyle
Gu
ide
stra
teg
y in
19
85
Ap
ple
Sty
le G
uid
e st
rate
gy
in 1
98
5
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2424
Ava
ilabi
lity
Ava
ilabi
lity
A
cces
s to
task
(un
natu
ral t
ask
sequ
ence
, A
cces
s to
task
(un
natu
ral t
ask
sequ
ence
, h
idd
en c
on
tro
ls)
hid
den
co
ntr
ols
)
A
cces
s to
info
rmat
ion
A
cces
s to
info
rmat
ion
--m
isp
lace
d in
wro
ng
mis
pla
ced
in w
rong
ta
sk w
ind
owta
sk w
ind
ow
H
idd
en c
on
tro
lsH
idd
en c
on
tro
ls
Im
pro
per
gro
upi
ng o
f men
u it
ems
and
data
Imp
rop
er g
rou
ping
of m
enu
item
s an
d da
ta
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2525
Fee
dbac
kF
eedb
ack
E
very
use
r ac
tion
mu
st in
voke
a r
esp
onse
Eve
ry u
ser
actio
n m
ust
invo
ke a
res
pon
se
In
dic
ates
eve
ryth
ing
is O
K, i
npu
t acc
epte
dIn
dic
ates
eve
ryth
ing
is O
K, i
npu
t acc
epte
d
C
ritic
al ta
sks
requ
ire d
iffer
ent f
eedb
ack
Crit
ical
task
s re
quire
diff
eren
t fee
dbac
k
P
rovi
de
clea
r in
form
atio
n, w
arn
ing
, and
P
rovi
de
clea
r in
form
atio
n, w
arn
ing
, and
er
ror
mes
sag
eser
ror
mes
sag
es
D
onD
on’’ t
let f
eed
back
get
in th
e w
ayt l
et fe
edba
ck g
et in
the
way
U
se R
edu
ndan
t fee
dbac
kU
se R
edu
ndan
t fee
dbac
k
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2626
Err
or H
andl
ing
Err
or H
andl
ing
D
esig
n fo
r fo
rgiv
enes
s D
esig
n fo
r fo
rgiv
enes
s --ac
com
mod
ate
use
r ac
com
mod
ate
use
r ex
plo
ratio
n an
d m
ista
kes
exp
lora
tion
and
mis
take
s
D
esig
n to
avo
id e
rro
rs (
edits
, UI c
ontr
ols
)D
esig
n to
avo
id e
rro
rs (
edits
, UI c
ontr
ols
)
E
ffect
ivel
y co
mm
un
icat
e an
d ex
pla
in e
rro
rsE
ffect
ivel
y co
mm
un
icat
e an
d ex
pla
in e
rro
rs
G
uid
e th
e u
ser
Gu
ide
the
use
r
A
llow
the
use
r to
rec
ove
r A
llow
the
use
r to
rec
ove
r
A
llow
the
use
r to
sta
y in
con
tro
lA
llow
the
use
r to
sta
y in
con
tro
l
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2727
Oth
er C
hara
cter
istic
s of
a U
sabl
e G
UI
Oth
er C
hara
cter
istic
s of
a U
sabl
e G
UI
P
ut u
ser
in c
ontr
ol
Pu
t use
r in
con
tro
l
UI i
s U
I is
““ tra
nspa
rent
tran
spar
ent ””to
the
user
to th
e us
er
U
ser
can
cust
omiz
e U
IU
ser
can
cust
omiz
e U
I
U
I is
resp
onsi
veU
I is
resp
onsi
ve
D
esig
n to
acc
omm
odat
e H
uman
Str
eng
ths
Des
ign
to a
ccom
mod
ate
Hum
an S
tren
gth
s an
d L
imita
tion
san
d L
imita
tion
s
Max
imiz
e H
uman
Per
form
ance
Max
imiz
e H
uman
Per
form
ance
U
se e
ffect
ive
gra
phic
des
ign
and
art
wo
rk.
Use
effe
ctiv
e g
raph
ic d
esig
n a
nd a
rtw
ork
.
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2828
Indu
stry
Sty
le G
uide
sIn
dust
ry S
tyle
Gui
des
O
SF
Mo
tif S
tyle
Gu
ide
V1
.2
OS
F M
otif
Sty
le G
uid
e V
1.2
--P
ren
tice
Hal
l P
ren
tice
Hal
l (I
SB
N(I
SB
N-- 00
-- 13
13 --
643
123
643
123 --
2)
2)
W
indo
ws
Inte
rfac
e W
indo
ws
Inte
rfac
e --A
n A
pplic
atio
n D
esig
n
An
App
licat
ion
Des
ign
G
uid
e (I
SB
NG
uid
e (I
SB
N --11 --
5561
555
615 --
384
384
-- 8)
8)
P
sych
olo
gy
of E
very
day
Th
ing
s P
sych
olo
gy
of E
very
day
Th
ing
s --D
r. D
on
Dr.
Don
A
. No
rman
A. N
orm
an
Jim
Ber
ney,
AM
/FM
Inte
rnat
iona
lJi
m B
erne
y, A
M/F
M In
tern
atio
nal
2929
Sum
mar
yS
umm
ary
D
efin
e ob
ject
ives
for
Usa
bili
tyD
efin
e ob
ject
ives
for
Usa
bili
ty
K
now
Thy
Use
r!K
now
Thy
Use
r!
In
volv
e us
ers
to d
o In
volv
e us
ers
to d
o Iter
ativ
eIt
erat
ive
Use
r C
ente
red
Use
r C
ente
red
Des
ign
.....
Des
ign
.....
A
nal
ysis
An
alys
is
D
esig
nD
esig
n
U
sab
ility
Tes
ting
Usa
bili
ty T
estin
g
F
ollo
w G
UI S
tyle
Gu
ide
con
ven
tions
Fo
llow
GU
I Sty
le G
uid
e co
nve
ntio
ns
