twang (version 0.6-1)

stop.methods: Rules for selecting the propensity scores

Description

A list of stop.method objects built into the twang package that encode rules for selecting propensity score weights

Details

The ps function uses a stop.method object for instructions on how to select the propensity score weights. twang has some stop.method objects built in but the user may implement their own if they wish and pass them to ps for it to optimize. A valid stop.method object is a list that defines the following metric{a function that evaluates the similarity of the distribution of a variable across the treatment and control groups. Currently, the twang package has functions es.stat, ks.stat, and strata.stat. The user may implement their own.} rule.summary{a function that takes the vector of results from the metric function and summarizes them into a single number. twang currently utilizes mean and max for rule.summary} direct{logical. If TRUE then ps will try to optimize the weights directly rather than utilizing gbm} na.action{a character string indicating how bal.stat should handle missing values. Current options are "level", "exclude", or "lowest"} name{a character string, preferably unique from other stop.methods for labeling the resulting weights} In addition, the object must have class(mystopmethod) <- "stop.method"