Add additional text outside of dotwhisker plot - r

Question

I have a tidy dataframe with multiple models that I'm plotting as a dotwhisker plot. Below I've recreated a similar dataframe. This plot requires a caption explaining information about the predictors, and ideally it would go underneath the legend. I have tried doing this as a caption, tag, and annotation, and each time the addition of the brackets on the side causes a problem with the formatting. Is there a way to add additional text here without the brackets causing a formatting issue?
#create dataframe
results_df <- data.frame(
model = c("Model 1", "Model 1", "Model 1",
"Model 1", "Model 1", "Model 1",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2",
"Model 3", "Model 3", "Model 3",
"Model 3", "Model 3", "Model 3",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2"),
estimate = c(-0.4890, 0.0966, -0.0911, -0.1700, 0.3620, 0.1980, -2.0920,
-1.1620, -1.6910,-1.5320, -0.8340, -1.4350, 0.8240, 0.9750,
0.9650, 0.5210, 0.9190, 0.9560, -0.9580, -0.1950, -1.1470,
-2.6430,-1.7420, -2.2500, -2.9990, -1.8100, -1.8270),
conf.low = c(-0.6, 0.0, -0.2,-0.6, 0.0, -0.2, -2.4, -1.8, -1.9, -2.4,
-1.8, -1.9, 0.0, 0.0, 0.0, 0.0, 0.0,0.0, -3.0, -2.0,
-1.9, -5.6, -3.6, -3.8, -3.0, -2.0, -1.9),
conf.high = c(0.9, 1.1, 1.0, 0.9, 1.1, 1.0, 0.0, 0.5, 0.7, 0.0, 0.5, 0.7,
0.9, 1.1, 1.0, 0.9, 1.1, 1.0, 0.0, 0.5, 0.7, 0.0,0.5, 0.7,
0.0, 0.5, 0.7),
term = c("A","B","C","A","B","C","A","B","C","A",
"B","C","A","B","C","A","B","C","D","E",
"F","G","H","I","J","K",
"L"),
fixed = c("Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects",
"With Fixed Effects", "With Fixed Effects", "With Fixed Effects",
"Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects",
"With Fixed Effects", "With Fixed Effects", "With Fixed Effects",
"Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects",
"With Fixed Effects", "With Fixed Effects", "With Fixed Effects",
"Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects",
"Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects",
"Without Fixed Effects", "Without Fixed Effects", "Without Fixed Effects"),
type = c("Model 1", "Model 1", "Model 1",
"Model 1", "Model 1", "Model 1",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2",
"Model 3", "Model 3", "Model 3",
"Model 3", "Model 3", "Model 3",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2",
"Model 2", "Model 2", "Model 2")
)
#recode model
results_df$model = results_df$type
#create dotwhisker
full_graph = dwplot(results_df,
vline = geom_vline(xintercept = 0, colour = "grey60", linetype = 2),
dot_args = list(aes(shape = fixed)),
whisker_args = list(aes(colour = model)))
#add graph elements
full_graph = full_graph +
theme_bw() +
theme(legend.justification=c(.02, .993),
legend.background = element_rect(color="gray90"),
plot.title = element_text(hjust = 0.52)) + #here is where I've tried using plot.caption and plot.tag, plot.tag.position
xlab("Coefficient Estimate") +
geom_vline(xintercept = 0, colour = "grey60", linetype = 2) +
ggtitle("Graph Title") +
scale_color_manual(name="Model",values=c("#52D871","#17D0E5","#EF5B3D"),
na.translate = F)+
scale_shape_manual(name = "Shape",values=c(16,17,16,17,16,17), na.translate = F)+
scale_fill_manual(name="Model",values = c("#52D871","#17D0E5","#EF5B3D"),
na.translate = F)
#add brackets
brackets = list(c("Bracket 1", "A", "C"),
c("Bracket 2", "D", "F"),
c("Bracket 3", "G", "I"),
c("Bracket 4","J","L"))
full_plot = full_graph %>% add_brackets(brackets)
Image of graph:

Answer 1

I'm not sure what you mean by the formatting being messed up. You could add a caption under the legend like this:
full_plot +
labs(caption = "Here's a caption explaining
what the different colors
and shapes represent ") +
theme(plot.caption = element_text(vjust = 70, hjust = 0.9, size = 12))