[R] Cross-Validation for Zero-Inflated Models

[lara harrup (IAH-P)]

Hi all
 
I have developed a zero-inflated negative binomial model using the
zeroinfl function from the pscl package, which I have carried out model
selection based on AIC and have used likelihood ratio tests (lrtest from
the lmtest package) to compare the nested models  [My end model contains
2 factors and 4 continuous variables in the count model plus one
continuous variable in the zero-inflated portion].
 
But for model assessment I would like to carry out some form of internal
cross-validation along the lines of leave one out cv etc, to gauge the
predictive ability of my final model just wondering if there is any
technique within r for doing this with zero-inflated models/negative
binomial models.
 
n.b. my data set is not large enough to split the data at the start and
only fit the model to a subset of data.
I am using r 2.8.1
 
Many Thanks in Advance
 
Lara