  A statistical model of the polarization of pulsar radio emission is used to
derive the general statistics of a polarization vector's orientation angles.
The theoretical distributions are compared with orientation angle histograms
computed from single-pulse, polarization observations of PSR B2020+28. The
favorable agreement between the theoretical and measured distributions lends
support to the underlying assumptions of the statistical model, and
demonstrates, like recent work on other pulsars, that the handedness of
circular polarization is associated with the radiation's orthogonally polarized
modes. Comprehensive directional statistics of the vector's orientation angles
are also derived, and are shown to follow the Watson bipolar and Fisher
distributions in its limiting forms.
