  A recent analysis by de Barros and Suppes of experimentally realizable GHZ
correlations supports the conclusion that these correlations cannot be
explained by introducing local hidden variables. We show, nevertheless, that
their analysis does not exclude local hidden variable models in which the
inefficiency in the experiment is an effect not only of random errors in the
detector equipment, but is also the manifestation of a pre-set, hidden property
of the particles ("prism models"). Indeed, we present an explicit prism model
for the GHZ scenario; that is, a local hidden variable model entirely
compatible with recent GHZ experiments.
