Compute Confidence Intervals for Fixed Effects in a Linear Mixed Model

This function calculates confidence intervals for the fixed effects of a fitted linear mixed-effects model (of class rlmerMod). The intervals are computed based on the estimated coefficients and their standard errors using a normal distribution.

Usage

# S3 method for class 'rlmerMod'
confint(mod, parm, level = 0.95)

Arguments

mod

A fitted linear mixed-effects model object of class rlmerMod. This is typically created using the rlmer function from the robustlmm package.

parm

A character vector specifying which parameters (fixed effects) to compute confidence intervals for. If missing, confidence intervals for all fixed effects are computed.

level

A numeric value between 0 and 1 indicating the confidence level for the intervals. The default is 0.95 for 95% confidence intervals.

Value

A matrix of confidence intervals for the specified fixed effects. Each row corresponds to a fixed effect, with columns representing the lower and upper bounds of the confidence intervals.

Examples

library(robustlmm)
#> Loading required package: lme4
#> Loading required package: Matrix
# Fit a linear mixed-effects model
mod <- rlmer(Reaction ~ Days + (Days | Subject), data = sleepstudy)
# Compute 95% confidence intervals for all fixed effects
confint(mod)
#>                   2.5%     97.5%
#> (Intercept) 236.976956 265.48981
#> Days          7.455326  13.84218
# Compute 99% confidence intervals for specific parameters
confint(mod, parm = "Days", level = 0.99)
#>      0.5%     99.5% 
#>  6.451878 14.845632