  The non-Euclidean geometry of spacetime induces an anisotropy in the apparent
correlation function of high-redshift quasars. This effect can constrain the
cosmological constant \Lambda independent of any assumptions about evolution of
luminosities, sizes, or clustering. We examine the prospects for distinguishing
between low-density (\Omega_0=0.1-0.4) cosmological models with flat and open
space geometry using the quasar samples anticipated from the 2dF and Sloan
redshift surveys. We show that even these large quasar surveys are likely to
reside in the "sparse sampling" regime, so that measurement errors in the
correlation function obey Poisson statistics. As a result: (a) one can devise a
simple maximum-likelihood scheme for estimating clustering parameters, (b) one
can generate Monte Carlo realizations of correlation function measurements
without creating artificial quasar distributions, and (c) for fixed quasar
number, a deeper survey over a smaller area has greater statistical power than
a shallow, large-area survey. Adopting recent (quite uncertain) estimates of
the quasar correlation length, we find that the 2dF and Sloan samples can
provide clear discrimination between flat and open geometries for \Omega <= 0.2
but only marginal discrimination for \Omega = 0.4. Clear discrimination is
possible for \Omega = 0.4 if the true quasar correlation length is a factor of
two larger, and a high-density survey of 30,000 quasars in 200 square degrees
would provide clear discrimination even for the lower correlation length.
