Caterpillar and Q-Q plots of random effects

plot() on the result of ranef() draws a caterpillar plot (dot chart) of the conditional modes for each grouping factor and coefficient, with levels sorted by their value and, when the object carries conditional variances (ranef(fit, condVar = TRUE)), level prediction intervals, mirroring lattice::dotplot() on lme4's ranef() output. qqnorm() draws normal Q-Q plots of the conditional modes, one panel per grouping factor and coefficient.

Usage

# S3 method for class 'mm_ranef'
plot(x, level = 0.95, type = c("caterpillar", "qq"), ...)

# S3 method for class 'mm_ranef'
qqnorm(y, ...)

Arguments

x, y

An mm_ranef object from ranef().

level

Coverage of the intervals (default 0.95).

type

"caterpillar" (default) or "qq".

...

Further graphical parameters passed to graphics::plot().

Value

x (or y), invisibly.

Details

When the lattice package is loaded, lattice::dotplot() and lattice::qqmath() also work on ranef() output and return one trellis object per grouping factor, as they do for lme4.

Intervals are omitted for coefficients whose conditional variances are not available (for example GLMM fits where ranef(condVar = TRUE) returns NA variances).

Examples

set.seed(1)
df <- data.frame(
  y = rnorm(60), x = rnorm(60),
  g = factor(rep(seq_len(10), each = 6))
)
fit <- lmm(y ~ x + (1 | g), df, control = mm_control(verbose = -1))
re <- ranef(fit, condVar = TRUE)
plot(re)

qqnorm(re)