Speaking Stata: Tables as lists: The groups command

Tables can often be conveniently considered or produced as lists. The list command is therefore a vehicle for obtaining such tables. The groups command for tabulation is built around a call to list. It has no particular limits on the number of identifiers (row, column, or other variables defining cells). Among other features, it offers support for various kinds of frequencies, percents, and cumulations thereof; for various subsetting and ordering by frequencies, percents, and so on; for reordering of columns from the default display; and for saving tabulated data to new datasets.