tab_subset() creates subsets using the levels of vrby, and tabulates
vr in each subset. Optionally, only use the lvls levels of vrby.
vr can be categorical (factor or character), logical, or numeric.
tab_cross() crosses or interacts vr and vrby and tabulates the new
variable. Tables created using tab_subset() and tab_cross() have the same
counts but different percentages. With tab_subset(), percentages within each
subset add up to 100%. With tab_cross(), percentages across the entire
population add up to 100%. Also see var_cross().
test = TRUE performs a test of association between the two variables. Also
performs t-tests for all pairs of levels of vr and vrby.
test = "{LEVEL}", where {LEVEL} is a level of vr, performs a
conditional independence test to compare the proportion of
vr = "{LEVEL}" for different values of vrby.