1-6 Sensors and Sensor Technology
2. Data outliers: Outliers are sensor values that deviate from the typical, or sometimes also meaning-
ful,
ra
nges
of th
e
me
asured
val
ues
. On
e
ca
n
di
stinguish
be
tween
tw
o
ty
pes
of ou
tliers,
na
mely,
ob
vi-
ous
ou
tliers
an
d
no
nobvious
ou
tliers
[2
9]
. Ob
vious
ou
tliers
ar
e
th
ose
val
ues
th
at
vi
olate
th
e
ph
ysical
or tec
hnological
li
mitations
. Fo
r
ex
ample,
th
e
ab
solute
pr
essure
ma
y
no
t
re
ach
ne
gative
val
ues
or
th
e
o
w
sen
sor
ma
y
no
t
de
liver
val
ues
th
at
ex
ceed
th
e
tec
hnological
li
mitations
of th
e
sen
sor
. To be
ab
le
to de
tect
th
is
ty
pe
of ou
tlier
e
ciently,
th
e
sy
stem
ha
s
to be pr
ovided
wi
th
th
e
li
miting
val
ues
in
th
e
fo
rm
of a pr
iori
in
formation
.
In co
ntrast
to th
is,
no
nobvious
ou
tliers
ar
e
ev
en
ha
rder
to id
entify