  When the target variable exhibits a semicontinuous behaviour (i.e. a point
mass in a single value and a continuous distribution elsewhere) parametric
`two-part regression models' have been extensively used and investigated. In
this paper, a semiparametric Bayesian two-part regression model for dealing
with such variables is proposed. The model allows a semiparametric expression
for the two part of the model by using Dirichlet processes. A motivating
example (in the `small area estimation' framework) based on pseudo-real data on
grapewine production in Tuscany, is used to evaluate the capabilities of the
model. Results show a satisfactory performance of the suggested approach to
model and predict semicontinuous data when parametric assumptions
(distributional and/or relationship) are not reasonable.
