Fits, on the A horizons of a set of pedons that record both colours, a
linear model of the dry Munsell value on the moist value and of the dry
chroma on the moist chroma, and estimates its error by cross-validation
grouped by pedon (the horizons of a pedon stay in one fold): the range of
the out-of-fold errors that holds
level of them (from its lower to its upper tail). The pedons are
dealt to the folds in turn, in the order given, so the result does not
depend on the random number generator. On the NPDB the
error is close to one value unit, so the estimate decides the dry value of
5.5 of the chernozemic A for most dark A horizons but seldom the limits of
3.5 and 4.5 between the Black, Dark Brown and Brown Chernozems.
Arguments
- pedons
A list of
PedonRecord.- level
Share of the cross-validated errors the range holds.
- folds
Number of folds.
Value
A list of class npdb_dry_colour_model: value and
chroma (each with coef, band = the error range,
rmse out of fold, n horizons), level.