The effective sample size is the sum of the harmonic means of the number units in treatment and control for each matched group. For k matched pairs, the effective sample size is k. As matched groups become more unbalanced, the effective sample size decreases.

## Usage

effectiveSampleSize(x, z = NULL)

# S3 method for factor
effectiveSampleSize(x, z = NULL)

# S3 method for default
effectiveSampleSize(x, z = NULL)

# S3 method for table
effectiveSampleSize(x, z = NULL)

## Arguments

x

An optmatch object, the result of fullmatch or pairmatch.

z

A treatment indicator, a vector the same length as match. This is only required if the match object does not contain the contrast.group' attribute.

## Value

The equivalent number of pairs in this match.

summary.optmatch, stratumStructure