sjstats (version 0.7.1)

re_var: Random effect variances

Description

These functions extracts random effect variances as well as random-intercept-slope-correlation of mixed effects models. Currently, only merMod objects are supported.

Usage

re_var(x)
get_re_var(x, comp = c("tau.00", "tau.01", "tau.11", "rho.01", "sigma_2"))

Arguments

x

Fitted mixed effects model (merMod-class). get_re_var() also accepts an object of class icc.lme4, as returned by the icc function.

comp

Name of the variance component to be returned. See 'Details'.

Value

get_re_var() returns the value of the requested variance component, re_var() returns NULL.

Details

The random effect variances indicate the between- and within-group variances as well as random-slope variance and random-slope-intercept correlation. Use following values for comp to get the particular variance component:

References

Aguinis H, Gottfredson RK, Culpepper SA. 2013. Best-Practice Recommendations for Estimating Cross-Level Interaction Effects Using Multilevel Modeling. Journal of Management 39(6): 1490–1528 (\Sexpr[results=rd,stage=build]{tools:::Rd_expr_doi("#1")}10.1177/0149206313478188http://doi.org/10.1177/0149206313478188doi:\ifelse{latex}{\out{~}}{ }latex~ 10.1177/0149206313478188 )

See Also

icc

Examples

library(lme4)
fit1 <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)

# all random effect variance components
re_var(fit1)

# just the rand. slope-intercept covariance
get_re_var(fit1, "tau.01")

sleepstudy$mygrp <- sample(1:45, size = 180, replace = TRUE)
fit2 <- lmer(Reaction ~ Days + (1 | mygrp) + (Days | Subject), sleepstudy)
re_var(fit2)