Calculate table of differences in means, medians, etc. for each
combination (or permutation, if using Monte Carlo approx.),
as needed in order to compute a confidence interval using cint
and/or a p-value using pval.
Threshold for whether to use Monte Carlo draws or complete
enumeration. If the number of all possible combinations
choose(n1+n2, n1) <= nmc, we use complete enumeration.
Otherwise, we take a Monte Carlo sample of nmc permutations.
You can set nmc = 0 to force complete enumeration regardless of
how many combinations there are.
returnData
Whether the returned dataframe should include columns for
the permuted data itself (if TRUE), or only the derived columns that are
needed for confidence intervals and p-values (if FALSE, default).
Value
A data frame ready to be used in cint() or pval().