  It is shown that the ratio of the deuteron and proton analysing powers in
proton-deuteron elastic scattering at small angles is sensitive to subtle
effects in a theoretical description. These include the transverse spin-spin
term in the elementary nucleon-nucleon amplitudes and double-scattering
corrections. On the other hand there is far less sensitivity to the spin-orbit
amplitude and to binding or other kinematic effects associated with the use of
the deuteron, as either target or projectile. The available data are in
agreement with the results of a refined Glauber theory model.
