Additional Arguments for Subclassification

• sub.by: criteria for subclassification. Choose from: "treat" (default), the number of treatment units; "control", the number of control units; or "all", the total number of units. Changing the default will likely also signal a change in your quantity of interest from the average treatment effect on the treated to other quantities.
• subclass: either a scalar specifying the number of subclasses, or a vector of probabilities bounded between 0 and 1, which create quantiles of the distance measure using the units in the group specified by sub.by (default = subclass = 6).