  In this paper, a new geometry index of Very Long Baseline Interferometry
(VLBI) observing networks, the volume of network $V$, is examined as an
indicator of the errors in the Earth orientation parameters (EOP) obtained from
VLBI observations. It has been shown that both EOP precision and accuracy can
be well described by the power law $\sigma=aV^c$ in a wide range of the network
size from domestic to global VLBI networks. In other words, as the network
volume grows, the EOP errors become smaller following a power law. This should
be taken into account for a proper comparison of EOP estimates obtained from
different VLBI networks. Thus performing correct EOP comparison allows us to
accurately investigate finer factors affecting the EOP errors. In particular,
it was found that the dependence of the EOP precision and accuracy on the
recording data rate can also be described by a power law. One important
conclusion is that the EOP accuracy depends primarily on the network geometry
and to lesser extent on other factors, such as recording mode and data rate and
scheduling parameters, whereas these factors have stronger impact on the EOP
precision.
