<s>
In	O
statistics	O
,	O
Stein	B-General_Concept
's	I-General_Concept
unbiased	I-General_Concept
risk	I-General_Concept
estimate	I-General_Concept
(	O
SURE	O
)	O
is	O
an	O
unbiased	O
estimator	O
of	O
the	O
mean-squared	B-Algorithm
error	I-Algorithm
of	O
"	O
a	O
nearly	O
arbitrary	O
,	O
nonlinear	O
biased	O
estimator.	O
"	O
</s>
<s>
This	O
is	O
important	O
since	O
the	O
true	O
mean-squared	B-Algorithm
error	I-Algorithm
of	O
an	O
estimator	O
is	O
a	O
function	O
of	O
the	O
unknown	O
parameter	O
to	O
be	O
estimated	O
,	O
and	O
thus	O
cannot	O
be	O
determined	O
exactly	O
.	O
</s>
<s>
The	O
importance	O
of	O
SURE	O
is	O
that	O
it	O
is	O
an	O
unbiased	O
estimate	O
of	O
the	O
mean-squared	B-Algorithm
error	I-Algorithm
(	O
or	O
squared	O
error	O
risk	O
)	O
of	O
,	O
i.e.	O
</s>
