interactions: an option to calculate summary statistics
in sum.all and sum.matched for all covariates,
their squares, and two-way interactions when interactions =
TRUE and only the covariates themselves when interactions
= FALSE, (DEFAULT = FALSE).
addlvariables: additional variables on which to
calculate the diagnostic statistics (in addition to the variables
included in the matching procedure) (DEFAULT = NULL).
addlvariables: a data frame containing additional variables
whose balance is examined. The data should come with the same number
of units and units in the same order as in the data set used for
matchit().
standardize: a logical variable indicating whether to
standardize balance measures, i.e., whether the difference in means should be divided
by the standard deviation in the original treated group. (DEFAULT = FALSE)
