data(cvq2.sample.B)
x
y
cvq2
.
The cross-validation applied to determine $q^2$ can be performed either as Leave-One-Out ($nFold = N = 6$) or as k-fold ($nFold = 2,3$).
In case $nFold = 2,3$ modelData
is randomly split into nFold
disjunct and equal sized test sets.
Furthermore one has the opportunity to repeat the cross-validation, while each run ($nRun=2,3\ldots, x$) has an individual test set compilation.
The prediction power, $q^2_cv$, calculated for this data set is considerably smaller than the model calibration, $r^2$, promises.
cvq2
,
q2