  The invariant imbedding evolution equations for the amplitude reflection and
transmission coefficients of a disordered 1D chain are shown to follow from the
continuum limit, for weak disorder, of recursion relations between reflection
(transmission) coefficients of Anderson chains of N and N-1 atoms embedded in
infinite non-disordered chains. We show that various available analytical and
numerical results for reflection phase distributions in the Anderson- and
invariant imbedding models are in good qualitative agreement, as expected from
the above equivalence of these models. We also discuss the distribution of
reflection phases and of reflection delay times for an Anderson model with a
simple distribution of on-site potentials characterizing extreme strong
disorder.
