<s>
Distribution-free	B-General_Concept
(	O
nonparametric	B-General_Concept
)	O
control	B-General_Concept
charts	I-General_Concept
are	O
one	O
of	O
the	O
most	O
important	O
tools	O
of	O
statistical	O
process	O
monitoring	O
and	O
control	O
.	O
</s>
<s>
Implementation	O
techniques	O
of	O
distribution-free	B-Application
control	I-Application
charts	I-Application
do	O
not	O
require	O
any	O
knowledge	O
about	O
the	O
underlying	O
process	O
distribution	O
or	O
its	O
parameters	O
.	O
</s>
<s>
The	O
main	O
advantage	O
of	O
distribution-free	B-Application
control	I-Application
charts	I-Application
is	O
its	O
in-control	O
robustness	O
,	O
in	O
the	O
sense	O
that	O
,	O
irrespective	O
of	O
the	O
nature	O
of	O
the	O
underlying	O
process	O
distributions	O
,	O
the	O
properties	O
of	O
these	O
control	B-General_Concept
charts	I-General_Concept
remain	O
the	O
same	O
when	O
the	O
process	O
is	O
smoothly	O
operating	O
without	O
presence	O
of	O
any	O
assignable	O
cause	O
.	O
</s>
<s>
Early	O
research	O
on	O
nonparametric	B-General_Concept
control	B-General_Concept
charts	I-General_Concept
may	O
be	O
found	O
in	O
1981	O
when	O
P.K.	O
</s>
<s>
Bhattacharya	O
and	O
D	O
.	O
Frierson	O
introduced	O
a	O
nonparametric	B-General_Concept
control	B-General_Concept
chart	I-General_Concept
for	O
detecting	O
small	O
disorders	O
.	O
</s>
<s>
However	O
,	O
major	O
growth	O
of	O
nonparametric	B-General_Concept
control	O
charting	O
schemes	O
has	O
taken	O
place	O
only	O
in	O
the	O
recent	O
years	O
.	O
</s>
<s>
There	O
are	O
distribution-free	B-Application
control	I-Application
charts	I-Application
for	O
both	O
Phase-I	O
analysis	O
and	O
Phase-II	O
monitoring	O
.	O
</s>
<s>
One	O
of	O
the	O
most	O
notable	O
distribution-free	B-Application
control	I-Application
charts	I-Application
for	O
Phase-I	O
analysis	O
is	O
RS/P	O
chart	O
proposed	O
by	O
G	O
.	O
Capizzi	O
and	O
G	O
.	O
Masaratto	O
.	O
</s>
<s>
RS/P	O
charts	O
separately	O
monitor	O
location	O
and	O
scale	O
parameters	O
of	O
a	O
univariate	B-General_Concept
process	O
using	O
two	O
separate	O
charts	O
.	O
</s>
<s>
In	O
2019	O
,	O
Chenglong	O
Li	O
,	O
Amitava	O
Mukherjee	O
and	O
Qin	O
Su	O
proposed	O
a	O
single	O
distribution-free	B-Application
control	I-Application
chart	I-Application
for	O
Phase-I	O
analysis	O
using	O
multisample	O
Lepage	O
statistic	O
.	O
</s>
<s>
Some	O
popular	O
Phase-II	O
distribution-free	B-Application
control	I-Application
charts	I-Application
for	O
univariate	B-General_Concept
continuous	O
processes	O
includes	O
:	O
</s>
