A simple helper function that takes a LogisticLogNormalOrdinal and an
integer grade and converts them to the equivalent LogisticLogNormal model.
h_convert_ordinal_model(x, grade)A LogisticLogNormal model.
(LogisticLogNormalOrdinal)
the LogisticLogNormalOrdinal
model to covert
(integer)
the toxicity grade for which the equivalent model
is required.