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I have two glmer models with two covariates each that I'm trying to plot into a single figure.

MWE:

## generalized linear mixed model
library(lattice)

cbpp$response <- sample(c(0,1), replace=TRUE, size=nrow(cbpp))
gm1 <- glmer(response ~ size + incidence + (1 | herd),
              data = cbpp, family = binomial)

cbpp$obs <- 1:nrow(cbpp)
gm2 <- glmer(response ~ size + incidence + (1 | herd) +  (1|obs),
              family = binomial, data = cbpp)

I am trying to plot the predicted values againts each covariate for each model. I found the sjPlot library and the plot_model function, which can plot these predictions when using type = "pred". Calling this function individually on each model works perfect and yields two separate figures like this for each model:

enter image description here

However I'm not familiar with R and I am having a hard time trying to plot the 4 plots on the same figure.

The plot_model function has a grid parameter, which only works for models with a Poisson distirbution. For gm1 and gm2, I am getting the following error when I call plot_model(gm1, type = "pred", grid = TRUE): 

Error in if (attr(x, "logistic", exact = TRUE) == "1" && attr(x, "is.trial",  : missing value where TRUE/FALSE needed

Anyway, I would not be able to plot the three models in one figure using this so I tried three different approaches. First, I saw the plot_models function, which takes multiple models as input. When I try to pass the two models as arguments, calling plot_models(gm1, gm2) I get the following error:

Error: $ operator not defined for this S4 class

Second, I tried using the par function setting the mfrow and then calling plot_model again without success. I don't get any error but the plots keep showing as individual figures.

Third, I tried using the gridExtra library. Calling

p1 <- plot_model(gm1, type = "pred")
p2 <- plot_model(gm2, type = "pred")
grid.arrange(p1, p2)

results in the following error:

Error in gList(list(ppt = list(data = list(x = c(-2, -1, 0, 1, 2, 3, 4,  : only 'grobs' allowed in "gList"

Does anyone have an insight on this?

EDIT

Marcelo Villa-Piñeros
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    Please edit your post to include reproducible sample data and code to provide us with something to work. It's very difficult (i.e. impossible) to help with questions of the form "I'm getting error XYZ" without knowing anything about the data that caused the error(s). I recommend taking a look at how to provide a [minimal reproducible example/attempt](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example). – Maurits Evers May 04 '19 at 00:23

1 Answers1

3

This seems to work:

pp1 <- plot_model(gm1,type="pred")
pp2 <- plot_model(gm2,type="pred")
plot_grid(c(pp1,pp2))
Ben Bolker
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