  We propose a new empirical formula for the anomalous Hall effect in heavy
electron materials based on a phenomenological two-fluid description of the
f-electron states. The new formula incorporates two previous theories proposed
by Fert and Levy in 1987 and Kontani et al. in the early 1990s and takes into
account both incoherent and coherent skew scatterings from local and itinerant
f-electrons. We perform experimental analysis in several heavy electron
compounds and show that the new formula provides a consistent description of
the evolution of the Hall coefficient in the whole temperature range down to
only a few Kelvin.
