nl_icc: Intraclass correlation coefficients for a multilevel nl_fit...

In MultiSpline: Spline-Based Nonlinear Modeling for Multilevel and Longitudinal Data

Intraclass correlation coefficients for a multilevel nl_fit model

Description

Extracts variance components from a multilevel nl_fit object and computes intraclass correlation coefficients (ICCs) for each grouping level plus the residual.

The ICC for grouping factor g is defined as:

ICC_g = \frac{\sigma^2_g}{\sum_j \sigma^2_j + \sigma^2_\epsilon}

Usage

nl_icc(object, include_residual = TRUE)

Arguments

object	An nl_fit object returned by nl_fit that was fitted with one or more cluster variables (i.e., a multilevel model fitted via lme4::lmer() or lme4::glmer()).
include_residual	Logical; if TRUE (default), includes the residual variance component ICC_resid in the output so that all values sum to 1.

Value

A named numeric vector of ICCs, one per grouping factor (named ICC_<groupname>) plus Residual for the residual variance (when include_residual = TRUE). All values sum to 1.

See Also

nl_fit

Examples

## Not run: 
fit <- nl_fit(
  data    = mydata,
  y       = "math_score",
  x       = "SES",
  cluster = c("id", "schid"),
  df      = 4
)
nl_icc(fit)

## End(Not run)

MultiSpline documentation built on April 16, 2026, 9:06 a.m.