deff function

Design Effect and Intra-cluster Correlation

Computes the Kish design effect and corresponding intra-cluster correlation for a single cluster-sampled variable

deff(y, cluster)

Arguments

• y: variable to analyze
• cluster: a variable whose unique values indicate cluster membership. Any type of variable is allowed.

Returns

a vector with named elements n (total number of non-missing observations), clusters (number of clusters after deleting missing data), rho(intra-cluster correlation), and deff

(design effect).

Author(s)

Frank Harrell

Department of Biostatistics

Vanderbilt University

fh@fharrell.com

See Also

bootcov, robcov

Examples

set.seed(1)
blood.pressure <- rnorm(1000, 120, 15)
clinic <- sample(letters, 1000, replace=TRUE)
deff(blood.pressure, clinic)