  We present a simple toy model for a scalar-isoscalar two-point correlator,
which can serve as a testing ground for the extraction of resonance parameters
from Lattice QCD calculations. We discuss in detail how the model correlator
behaves when it is restricted to a finite spatial volume, and how the
finite-volume data can be used to reconstruct the spectral function of the
correlator in the infinite volume, which allows to extract properties of the
resonance from such data.
