  The memory effect in a single crystal spin glass
($\mathrm{Cu}_{0.92}\mathrm{Mn}_{0.08}$) has been measured using $1
\mathrm{Hz}$ ac susceptibility techniques over a reduced temperature range of
$0.4 - 0.7 \, T_g$ and a model of the memory effect has been developed. A
double-waiting-time protocol is carried out where the spin glass is first
allowed to age at a temperature below $T_g$, followed by a second aging at a
lower temperature after it has fully rejuvenated. The model is based on
calculating typical coincidences between the growth of correlated regions at
the two temperatures. It accounts for the absolute magnitude of the memory
effect as a function of both waiting times and temperatures. The data can be
explained by the memory loss being a function of the relative change in the
correlated volume at the first waiting temperature because of the growth in the
correlations at the second waiting temperature.
