  We present a new method to measure Gamma*theta_j in flux-limited samples of
active galactic nuclei (AGN) jets, where Gamma is the bulk Lorentz factor and
theta_j is the jet's half-opening angle. The Gamma*theta_j parameter is
physically important for models of jet launching, and also determines the
effectiveness of jet instabilities and magnetic reconnection. We measure
Gamma*theta_j by analyzing the observed distribution of apparent opening angles
in very long baseline interferometry (VLBI) flux-limited samples of jets, given
some prior knowledge of the active galactic nuclei (AGN) radio luminosity
function. We then apply this method to the MOJAVE flux-limited sample of radio
loud objects and find Gamma*theta_j = 0.1 +- 0.03, which implies that AGN jets
are subject to a variety of physical processes that require causal connection.
