dx.wts {twang}R Documentation

Propensity score diagnostics

Description

dx.wts takes a ps object or a set of propensity scores and computes diagnostics assessing covariates balance.

Usage

dx.wts(x,
       data,
       vars=NULL,
       treat.var,
       x.as.weights=TRUE,
       sampw=NULL,
       perm.test.iters=0,
       plots=TRUE,
       title)

Arguments

x a data frame, matrix, or vector of propensity score weights or a ps object. x can also be a data frame, matrix, or vector of propensity scores if x.as.weights=FALSE
data a data frame
vars a vector of character strings naming variables in data on which to assess balance
treat.var a character string indicating which variable in data contains the 0/1 treatment group indicator
x.as.weights TRUE or FALSE indicating whether x specifies propensity score weights or propensity scores. Ignored if x is a ps object
sampw optional sampling weights. If x is a ps object then the sampling weights should have been passed to ps and not specified here. dx.wts will issue a warning if x is a ps object and sampw is also specified
perm.test.iters an non-negative integer giving the number of iterations of the permutation test for the KS statistic. If perm.test.iters=0 then the function returns an analytic approximation to the p-value. This argument is ignored is x is a ps object. Setting perm.test.iters=200 will yield precision to within 3% if the true p-value is 0.05. Use perm.test.iters=500 to be within 2%
plots if plots=TRUE then dx.wts will call diag.plot generating diagnostic plots
title a short text title, it will be used in plots and saved files. By default this is set to the current date and time

Details

Creates a balance table that compares unweighted and weighted means and standard deviations, computes effect sizes, and KS statistics to assess the ability of the propensity scores to balance the treatment and control groups.

Value

Returns a list containing

treat the vector of 0/1 treatment assignment indicators
desc a nested list containing detailed diagnostic information on the weights. This includes the number of treatment and control subjects, the effective sample size, the largest KS statistic, the average absolute effect size, and the complete balance table
summary.tab a data frame showing balance information
ps the given propensity scores
w the given weights
datestamp the date and time of the call to dx.wts
parameters the parameters used when calling dx.wts
alerts text containing any warnings accumulated during the estimation

See Also

The example for ps contains an example of the use of dx.wts, diag.plot


[Package twang version 1.0-1 Index]