sdiff: Balance Measures

Description

Balance assessment for individual variables, before and after matching

Usage

sdiff(varname, treatment, orig.data, match.data = NULL, 
treat.wts = NULL, ctrl.wts = NULL, mt.wts = NULL, mc.wts = NULL)	
ttest.balance(varname, treatment, orig.data, match.data = NULL,
treat.wts = NULL, ctrl.wts = NULL, mt.wts = NULL, mc.wts = NULL)	
fisher.balance(varname, treatment, orig.data, match.data = NULL,
treat.wts = NULL, ctrl.wts = NULL, mt.wts = NULL, mc.wts = NULL)
wilc.balance(varname, treatment, orig.data, match.data = NULL,
treat.wts = NULL, ctrl.wts = NULL, mt.wts = NULL, mc.wts = NULL)

Arguments

varname

name of the variable on which to test balance

treatment

name of the binary indicator for treatment status

orig.data

a data frame containing the data before matching

match.data

an optional data frame containing the matched sample

treat.wts

optional weights for treated units in the original sample

ctrl.wts

optional weights for control units in the original sample

mt.wts

optional weights for treated units in the matched sample

mc.wts

optional weights for treated units in the matched sample

Value

a labeled vector. For sdiff, the vector has six elements if match.data is provided: treated and control means and standardized differences before and after matching. If match.data is not provided, the vector has only the three elements corresponding to the pre-match case. For the other functions, if match.data is provided, the vector contains p-values for the test before and after matching. Otherwise a single p-value is given for the pre-match data.

Details

The sdiff function computes the standardized difference in means. The other functions perform different kinds of balance tests: t.balance does the 2-sample t-test, fisher.balance does Fisher's exact test for binary variable, and wilc.balance does Wilcoxon's signed rank test.

References

Rosenbaum, Paul R. (2002). Observational Studies. Springer-Verlag.

Rosenbaum, Paul R. (2010). Design of Observational Studies. Springer-Verlag.