  The known population of pulsars contains objects with four and five component
profiles, for which the peak-to-peak separations between the inner and outer
components can be measured. These Q and M type profiles can be interpreted as a
result of sightline cut through a nested cone beam, or through a set of
azimuthal fan beams. We show that the ratio R_W of the components' separations
provides a useful measure of the beam shape, which is mostly independent of
parameters that determine the beam scale and complicate interpretation of
simpler profiles. In particular, the method does not depend on the emission
altitude and the dipole tilt distribution. The different structures of the
radio beam imply manifestly different statistical distributions of R_W, with
the conal model being several orders of magnitude less consistent with data
than the fan beam model. To bring the conal model into consistency with data,
strong effects of observational selection need to be called for, with 80% of Q
and M profiles assumed to be undetected because of intrinsic blending effects.
It is concluded that the statistical properties of Q and M profiles are more
consistent with the fan-shaped beams, than with the traditional nested cone
geometry.
