Visualizing Random Effects

[Aaron Gardony]

Using lme4 models I was able to plot random effects of using the command:

dotplot(ranef(lme4_model, postVar=TRUE))

When I try to use this command with the mixed model produced by afex I get the following error:

Error in UseMethod (“ranef”) :
no applicable method for ‘ranef’ applied to an object of class “mixed”

Do you have any guidance for how to visualize random effect with afex? Any advice would be appreciated!

[henrik]

The problem is that afex::mixed returns an object, of class "mixed", where the original lme4 object is in slot full_model:

library("afex")
data("Machines", package = "MEMSS") 
m1 <- mixed(score ~ Machine + (Machine|Worker), data=Machines)

str(m1, 1)
# List of 5
#  $ anova_table      :Classes ‘anova’ and 'data.frame':	1 obs. of  4 variables:
#   ..- attr(*, "heading")= chr [1:3] "Mixed Model Anova Table (Type 3 tests, KR-method)\n" "Model: score ~ Machine + (Machine | Worker)" "Data: Machines"
#   ..- attr(*, "sig_symbols")= chr [1:4] " +" " *" " **" " ***"
#  $ full_model       :Formal class 'merModLmerTest' [package "lmerTest"] with 13 slots
#  $ restricted_models: NULL
#  $ tests            : NULL
#  $ data             :'data.frame':	54 obs. of  3 variables:
#  - attr(*, "class")= chr "mixed"
#  - attr(*, "type")= num 3
#  - attr(*, "method")= chr "KR"

So one just needs to pass this slot to the corresponding function and not the whole object. This works for example via $:

library("lattice")
dotplot(ranef(m1$full_model, condV=TRUE))

Hope that helps!

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