Compute the effective sample size of a match.

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.

See also

summary.optmatch, stratumStructure