ANOVA Tables for Linear Mixed Models

ANOVA table with F-tests and p-values using Satterthwaite's or Kenward-Roger's method for denominator degrees-of-freedom and F-statistic. Models should be fitted with lmer from the lmerTest-package.

Usage

# S3 method for class 'lmerModLmerTest'
anova(
  object,
  ...,
  type = c("III", "II", "I", "3", "2", "1"),
  ddf = c("Satterthwaite", "Kenward-Roger", "lme4")
)

Arguments

object: an lmerModLmerTest object; the result of lmer() after loading the lmerTest-package.
...: potentially additional lmer or lm model objects for comparison of models in which case type and ddf arguments are ignored.
type: the type of ANOVA table requested (using SAS terminology) with Type I being the familiar sequential ANOVA table.
ddf: the method for computing the denominator degrees of freedom and F-statistics. ddf="Satterthwaite" (default) uses Satterthwaite's method; ddf="Kenward-Roger" uses Kenward-Roger's method, ddf = "lme4" returns the lme4-anova table, i.e., using the anova method for lmerMod objects as defined in the lme4-package and ignores the type argument. Partial matching is allowed.

Value

an ANOVA table

Details

The "Kenward-Roger" method calls pbkrtest::KRmodcomp internally and reports scaled F-statistics and associated denominator degrees-of-freedom.

Author

Rune Haubo B. Christensen and Alexandra Kuznetsova

Examples


data("sleepstudy", package="lme4")
m <- lmer(Reaction ~ Days + (Days | Subject), sleepstudy)
anova(m) # with p-values from F-tests using Satterthwaite's denominator df
#> Type III Analysis of Variance Table with Satterthwaite's method
#>      Sum Sq Mean Sq NumDF DenDF F value    Pr(>F)    
#> Days  30031   30031     1    17  45.853 3.264e-06 ***
#> ---
#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1
anova(m, ddf="lme4") # no p-values
#> Analysis of Variance Table
#>      npar Sum Sq Mean Sq F value
#> Days    1  30031   30031  45.853

# Use the Kenward-Roger method
if(requireNamespace("pbkrtest", quietly = TRUE))
  anova(m, ddf="Kenward-Roger")
#> Type III Analysis of Variance Table with Kenward-Roger's method
#>      Sum Sq Mean Sq NumDF DenDF F value    Pr(>F)    
#> Days  30031   30031     1    17  45.853 3.264e-06 ***
#> ---
#> Signif. codes:  0 ‘***’ 0.001 ‘**’ 0.01 ‘*’ 0.05 ‘.’ 0.1 ‘ ’ 1