arm: balance – R documentation

Pricing

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

Get Started for Free

Documentation

arm

balance

Functions to compute the balance statistics

Description

This function computes the balance statistics before and after matching.

Usage

balance(rawdata, treat, matched, estimand="ATT")

## S3 method for class 'balance'
print(x, ..., combined = FALSE, digits = 2)

## S3 method for class 'balance'
plot(x, longcovnames=NULL, which.covs="mixed",
    v.axis=TRUE, cex.main=1, cex.vars=1, cex.pts=1,
    mar=c(4, 3, 5.1, 2), plot=TRUE, x.max = NULL, ...)

Arguments

`rawdata`	The full covariate dataset
`treat`	the vector of treatment assignments for the full dataset
`matched`	vector of weights to apply to the full dataset to create the restructured data: for matching without replacement these will all be 0's and 1's; for one-to-one matching with replacement these will all be non-negative integers; for IPTW or more complicated matching methods these could be any non-negative numbers
`estimand`	can either be `ATT`, `ATC`, or `ATE`, default is `ATT`
`x`	an object return by the balance function.
`combined`	default is `FALSE`
`digits`	minimal number of significant digits, default is 2.
`longcovnames`	long covariate names. If not provided, plot will use covariate variable name by default
`which.covs`	`mixed` then it plots all as std diffs; `binary` it only plots binary and as abs unstd diffs; `cont` it only plots non-binary and as abs std diffs
`v.axis`	default is `TRUE`, which shows the top axis–axis(3).
`cex.main`	font size of main title
`cex.vars`	font size of variabel names
`cex.pts`	point size of the estimates
`mar`	A numerical vector of the form `c(bottom, left, top, right)` which gives the number of lines of margin to be specified on the four sides of the plot. The default is `c(0,3,5.1,2)`.
`plot`	default is `TRUE`, which will plot the plot.
`x.max`	set the max of the `xlim`, default is `NULL`
`...`	other plot options may be passed to this function

Details

This function plots the balance statistics before and after matching. The open circle dots represent the unmatched balance statistics. The solid dots represent the matched balance statistics. The closer the value of the estimates to the zero, the better the treated and control groups are balanced after matching.

Note

The function does not work with predictors that contain factor(x), log(x) or all other data transformation. Create new objects for these variables. Attach them into the original dataset before doing the matching procedure.

Author(s)

Jennifer Hill jennifer.hill@nyu.edu; Yu-Sung Su suyusung@tsinghua.edu.cn

References

Andrew Gelman and Jennifer Hill. (2006). Data Analysis Using Regression and Multilevel/Hierarchical Models. Cambridge University Press. (Chapter 10)

Examples

# matching first
old.par <- par(no.readonly = TRUE)
data(lalonde)
attach(lalonde)
fit <- glm(treat ~ re74 + re75 + age + factor(educ) + 
            black + hisp + married + nodegr + u74 + u75, 
            family=binomial(link="logit"))
pscores <- predict(fit, type="link")
matches <- matching(z=lalonde$treat, score=pscores)
matched <- matches$cnts

# balance check
b.stats <- balance(lalonde, treat, matched, estimand = "ATT")
print(b.stats)
plot(b.stats)
par(old.par)

arm

Data Analysis Using Regression and Multilevel/Hierarchical Models

v1.11-2

GPL (> 2)

Authors

Andrew Gelman [aut], Yu-Sung Su [aut, cre], Masanao Yajima [ctb], Jennifer Hill [ctb], Maria Grazia Pittau [ctb], Jouni Kerman [ctb], Tian Zheng [ctb], Vincent Dorie [ctb]

Initial release

2020-7-27