Uncertainties can influence
performance assessments in a number of
ways. Some sources of uncertainty can
be addressed, or at least accounted for,
while in other areas our knowledge may
be too limited to even characterize the
uncertainty, much less explicitly
account for it. Sources of uncertainty are
often discussed in broad categories such
as ‘‘data’’ or ‘‘model’’ uncertainty,
although these can take on various
forms within those broader categories
that create individual challenges.22