<s>
The	O
chemical	B-Application
shift	I-Application
index	I-Application
or	O
CSI	O
is	O
a	O
widely	O
employed	O
technique	O
in	O
protein	O
nuclear	O
magnetic	O
resonance	O
spectroscopy	O
that	O
can	O
be	O
used	O
to	O
display	O
and	O
identify	O
the	O
location	O
(	O
i.e.	O
</s>
<s>
It	O
was	O
these	O
rather	O
striking	O
chemical	O
shift	O
trends	O
that	O
were	O
exploited	O
in	O
the	O
development	O
of	O
the	O
chemical	B-Application
shift	I-Application
index	I-Application
.	O
</s>
<s>
In	O
particular	O
,	O
its	O
performance	O
drops	O
if	O
chemical	O
shift	O
assignments	O
are	O
mis-referenced	B-Application
or	O
incomplete	O
.	O
</s>
<s>
These	O
include	O
:	O
1	O
)	O
a	O
prediction	O
method	O
that	O
employs	O
statistically	O
derived	O
chemical	O
shift/structure	O
potentials	O
(	O
PECAN	O
)	O
;	O
2	O
)	O
a	O
probabilistic	O
approach	O
to	O
secondary	O
structure	O
identification	O
(	O
PSSI	O
)	O
;	O
3	O
)	O
a	O
method	O
that	O
combines	O
secondary	O
structure	O
predictions	O
from	O
sequence	O
data	O
and	O
chemical	O
shift	O
data	O
(	O
PsiCSI	O
)	O
,	O
4	O
)	O
a	O
secondary	O
structure	O
identification	O
approach	O
that	O
uses	O
pre-specified	O
chemical	O
shift	O
patterns	O
(	O
PLATON	O
)	O
and	O
5	O
)	O
a	O
two-dimensional	O
cluster	B-Algorithm
analysis	I-Algorithm
method	O
known	O
as	O
2DCSi	O
.	O
</s>
