<s>
In	O
statistical	O
quality	O
control	O
,	O
the	O
p-chart	B-Application
is	O
a	O
type	O
of	O
control	B-General_Concept
chart	I-General_Concept
used	O
to	O
monitor	O
the	O
proportion	O
of	O
nonconforming	O
units	O
in	O
a	O
sample	O
,	O
where	O
the	O
sample	O
proportion	O
nonconforming	O
is	O
defined	O
as	O
the	O
ratio	O
of	O
the	O
number	O
of	O
nonconforming	O
units	O
to	O
the	O
sample	O
size	O
,	O
n	O
.	O
</s>
<s>
The	O
p-chart	B-Application
only	O
accommodates	O
"	O
pass	O
"	O
/	O
"	O
fail	O
"	O
-type	O
inspection	O
as	O
determined	O
by	O
one	O
or	O
more	O
go-no	O
go	O
gauges	O
or	O
tests	O
,	O
effectively	O
applying	O
the	O
specifications	O
to	O
the	O
data	O
before	O
they	O
are	O
plotted	O
on	O
the	O
chart	O
.	O
</s>
<s>
Other	O
types	O
of	O
control	B-General_Concept
charts	I-General_Concept
display	O
the	O
magnitude	O
of	O
the	O
quality	O
characteristic	O
under	O
study	O
,	O
making	O
troubleshooting	O
possible	O
directly	O
from	O
those	O
charts	O
.	O
</s>
<s>
The	O
binomial	O
distribution	O
is	O
the	O
basis	O
for	O
the	O
p-chart	B-Application
and	O
requires	O
the	O
following	O
assumptions	O
:	O
</s>
<s>
Another	O
technique	O
is	O
to	O
choose	O
the	O
sample	O
size	O
large	O
enough	O
so	O
that	O
the	O
p-chart	B-Application
has	O
a	O
positive	O
lower	O
control	O
limit	O
or	O
.	O
</s>
<s>
In	O
the	O
case	O
of	O
100%	O
inspection	O
,	O
variation	O
in	O
the	O
production	O
rate	O
(	O
e.g.	O
,	O
due	O
to	O
maintenance	O
or	O
shift	O
changes	O
)	O
conspires	O
to	O
produce	O
different	O
sample	O
sizes	O
for	O
each	O
observation	O
plotted	O
on	O
the	O
p-chart	B-Application
.	O
</s>
<s>
Some	O
practitioners	O
have	O
pointed	O
out	O
that	O
the	O
p-chart	B-Application
is	O
sensitive	O
to	O
the	O
underlying	O
assumptions	O
,	O
using	O
control	O
limits	O
derived	O
from	O
the	O
binomial	O
distribution	O
rather	O
than	O
from	O
the	O
observed	O
sample	O
variance	O
.	O
</s>
<s>
Due	O
to	O
this	O
sensitivity	O
to	O
the	O
underlying	O
assumptions	O
,	O
p-charts	B-Application
are	O
often	O
implemented	O
incorrectly	O
,	O
with	O
control	O
limits	O
that	O
are	O
either	O
too	O
wide	O
or	O
too	O
narrow	O
,	O
leading	O
to	O
incorrect	O
decisions	O
regarding	O
process	O
stability	O
.	O
</s>
<s>
A	O
p-chart	B-Application
is	O
a	O
form	O
of	O
the	O
Individuals	B-Application
chart	I-Application
(	O
also	O
referred	O
to	O
as	O
"	O
XmR	O
"	O
or	O
"	O
ImR	O
"	O
)	O
,	O
and	O
these	O
practitioners	O
recommend	O
the	O
individuals	B-Application
chart	I-Application
as	O
a	O
more	O
robust	O
alternative	O
for	O
count-based	O
data	O
.	O
</s>
