  In efforts to determine phase transitions in the disintegration of highly
excited heavy nuclei, a popular practice is to parametrise the yields of
isotopes as a function of temperature in the form
$Y(z)=z^{-\tau}f(z^{\sigma}(T-T_0))$, where $Y(z)$'s are the measured yields
and $\tau, \sigma$ and $T_0$ are fitted to the yields. Here $T_0$ would be
interpreted as the phase transition temperature. For finite systems such as
those obtained in nuclear collisions, this parametrisation is only approximate
and hence allows for extraction of $T_0$ in more than one way. In this work we
look in detail at how values of $T_0$ differ, depending on methods of
extraction. It should be mentioned that for finite systems, this approximate
parametrisation works not only at the critical point, but also for first order
phase transitions (at least in some models). Thus the approximate fit is no
guarantee that one is seeing a critical phenomenon. A different but more
conventional search for the nuclear phase transition would look for a maximum
in the specific heat as a function of temperature $T_2$. In this case $T_2$ is
interpreted as the phase transition temperature. Ideally $T_0$ and $T_2$ would
coincide. We invesigate this possibility, both in theory and from the ISiS
data, performing both canonical ($T$) and microcanonical ($e=E^*/A$)
calculations. Although more than one value of $T_0$ can be extracted from the
approximate parmetrisation, the work here points to the best value from among
the choices. Several interesting results, seen in theoretical calculations, are
borne out in experiment.
