  The VSOP (VLBI Space Observatory Programme) mission is a Japanese-led project
to study radio sources with sub-milliarcsec angular resolution, using an
orbiting 8-m telescope on board the satellite HALCA with a global earth-based
array of telescopes. A major program is the 5 GHz VSOP Survey Program, which we
supplement here with VLBA observations to produce a complete and flux-density
limited sample. Using statistical methods of analysis of the observed
visibility amplitude versus projected (u,v) spacing, we have determined the
angular size and brightness temperature distribution of bright AGN radio cores.
On average, the cores have a diameter (full-width, half-power) of 0.20 mas
which contains about 20% of the total source emission, and (14+/-6)% of the
cores are <0.04 mas in size. About (20+/-5)% of the radio cores have a source
frame brightness temperature 10^{13}K, and (3+/-2)% have 10^{14}K. A model of
the high brightness temperature tail suggests that the radio cores have a
brightness temperatures approx 10^{12}K, and are beamed toward the observer
with an average bulk motion of v/c=0.993 +/- 0.004.
