  We study the Nernst effect in fluctuating superconductors by calculating the
transport coefficient $\alpha_{xy}$ in a phenomenological model where relative
importance of phase and amplitude fluctuations of the order parameter is tuned
continuously to smoothly evolve from an effective XY model to more conventional
Ginzburg-Landau description. To connect with a concrete experimental
realization we choose the model parameters appropriate for cuprate
superconductors and calculate $\alpha_{xy}$ and the magnetization ${\bf M}$
over the entire range of experimentally accessible values of field, temperature
and doping. We argue that $\alpha_{xy}$ and ${\bf M}$ are both determined by
the equilibrium properties of the superconducting fluctuations (and not their
dynamics) despite the former being a transport quantity. Thus, the
experimentally observed correlation between the Nernst signal and the
magnetization arises primarily from the correlation between $\alpha_{xy}$ and
${\bf M}$. Further, there exists a dimensionless ratio ${\bf M}/(T
\alpha_{xy})$ that quantifies this correlation. We calculate, for the first
time, this ratio over the entire phase diagram of the cuprates and find it
agrees with previous results obtained in specific parts of the phase diagram.
We conclude that that there appears to be no sharp distinction between the
regimes dominated by phase fluctuations and Gaussian fluctuations for this
ratio in contrast to $\alpha_{xy}$ and ${\bf M}$ individually. The utility of
this ratio is that it can be used to determine the extent to which
superconducting fluctuations contribute to the Nernst effect in different parts
of the phase diagram given the measured values of magnetization.
