  We report a high temperature (T = 0.3K) indicator of the excitation gap
$\Delta_{5/2}$ at the filling factor $ \nu=5/2$ fractional quantum Hall state
in ultra-high quality AlGaAs/GaAs two-dimensional electron gases. As the lack
of correlation between mobility $\mu$ and $\Delta_{5/2}$ has been well
established in previous experiments, we define, analyze and discuss the utility
of a different metric $\rho_{5/2}$, the resistivity at $\nu=5/2$, as a high
temperature predictor of $\Delta_{5/2}$. This high-field resistivity reflects
the scattering rate of composite fermions. Good correlation between
$\rho_{5/2}$ and $\Delta_{5/2}$ is observed in both a density tunable device
and in a series of identically structured wafers with similar density but
vastly different mobility. This correlation can be explained by the fact that
both $\rho_{5/2}$ and $\Delta_{5/2}$ are sensitive to long-range disorder from
remote impurities, while $\mu$ is sensitive primarily to disorder localized
near the quantum well.
