Currently, there is no check to ensure that either variables
submitted are factors.
Data should be ordinal. Nominal data may not have any practical meaning in
this test. Sometimes, when a nominal variable has only two levels, this
test may still be appropriate, i.e. Yes vs. No.
In 2xJ tables, when arbitrary scores (i.e., 0, 1) are applied to the rows
and midranks applied to the columns, this test is equivalent to the
Wilcoxon, or Mann-Whitney test.
In Ix2 tables, when monotone scores are applied to the rows and abitrary
scores applied to the columns, this test is equivalent to the
Cochran-Armitage test. See the reference for further details.