  RR Lyrae stars in the Milky Way are good tracers to study the kinematic
behaviour and spatial distribution of older stellar populations. A recently
established well documented sample of 217 RR Lyr stars with V<12.5 mag, has
been used to reinvestigate these structural parameters. The kinematic
parameters allowed to calculate the orbits of the stars. Nearly 1/3 of the
stars of our sample has orbits staying near the Milky Way plane. Of the 217
stars, 163 have halo-like orbits fulfilling one of the following criteria:
Theta < 100 km/s, orbit eccentricity >0.4, and normalized maximum orbital
z-distance >0.45. Of these stars roughly half have retrograde orbits. The
z-distance probability distribution of this sample shows scale heights of 1.3
+-0.1 kpc for the disk component and 4.6 +-0.3 kpc for the halo component. With
our orbit statistics method we found a (vertical) spatial distribution which,
out to z=20 kpc, is similar to that found with other methods. This distribution
is also compatible with the ones found for blue (HBA and sdB) halo stars. The
circular velocity Theta, the orbit eccentricity, orbit z-extent and [Fe/H] are
employed to look for possible correlations. If any, it is that the metal poor
stars with [Fe/H] <1.0 have a wide symmetric distribution about Theta=0. We
conclude that the Milky Way possesses a halo component of old and metal poor
stars with a scale height of 4-5 kpc having random orbits. The presence in our
sample of a few metal poor stars (thus part of the halo population) with thin
disk-like orbits is statistically not surprising. The midplane density ratio of
halo to disk stars is found to be 0.16, a value very dependent on proper sample
statistics. Keywords: astrometry -- Stars: kinematics -- Stars: variables --
Stars: RR-Lyrae -- Galaxy: Halo -- Galaxy: structure
