  Uncertainty quantification has emerged as a rapidly growing field in nuclear
science. Theoretical predictions of physical observables often involve
extrapolations to regions that are poorly constrained by laboratory experiments
and astrophysical observations. Without properly quantified theoretical errors,
such model predictions are of limited value. Also, one often deals with
theoretical constructs that involve fundamental quantities that are not
accessible to experiment or observation. Particularly relevant in this context
is the pressure of pure neutron matter. In this contribution we develop an
analytic framework to answer the question of "How can new data reduce
uncertainties of current theoretical models?" [P.-G. Reinhard and W.
Nazarewicz, Phys. Rev. C81, 051303(R) (2010)]. Simple and insightful
expressions are obtained to quantify the impact of one or two new observables
on theoretical uncertainties in two critical quantities: the slope of the
symmetry energy at saturation density and the pressure of pure neutron matter
at twice nuclear matter saturation density.
