  We compare two different approaches for quantization of the Bianchi I model:
a reduced phase space quantization, in which the isotropic Misner variables is
taken as time, and the Vilenkin proposal, in which a semiclassical
approximation is performed for the same variable. We outline the technical and
interpretative issues of these two methods and we demonstrate that they provide
equivalent results only if the dynamics is essentially dictated by the
isotropic matter contribution.
