Adding coefficient group titles to modelsummary output

Question

I'm trying to group coefficients together in a modelsummary output table and add row titles for these groups :

library(modelsummary)

ols1 <- lm(mpg ~ cyl + disp + hp,
  data = mtcars,
  na.action = na.omit
)

modelsummary(ols1,
  title = "Table 1",
  stars = TRUE
)

The modelsummary documentation (https://cran.r-project.org/web/packages/modelsummary/modelsummary.pdf) suggests this might be something to do with the shape and group_map arguments, but I can't really figure out how to use them.

Any guidance would be very helpful, thanks!

Answer 1

When the documentation mentions “groups”, it refers to models like multinomial logits where each predictor has one coefficient per outcome level. In this example, the “group” column is called “response”:

library(nnet)
library(modelsummary)

mod <- multinom(cyl ~ mpg + hp, data = mtcars, trace = FALSE)

modelsummary(
    mod,
    output = "markdown",
    shape = response ~ model)

		Model 1
(Intercept)	6	0.500
		(41.760)
	8	8.400
		(0.502)
mpg	6	-83.069
		(416.777)
	8	-120.167
		(508.775)
hp	6	16.230
		(81.808)
	8	20.307
		(87.777)
Num.Obs.		32
R2		1.000
R2 Adj.		0.971
AIC		12.0
BIC		20.8
RMSE		0.00

What you probably mean is something different: Adding manual labels to sets of coefficients. This is easy to achieve because modelsummary() produces a kableExtra or a gt table which can be customized in infinite ways.

https://cran.r-project.org/web/packages/kableExtra/vignettes/awesome_table_in_html.html

For example, you may want to look at the group_rows function from kableExtra:

library(kableExtra)
mod <- lm(mpg ~ cyl + disp + hp, data = mtcars)
modelsummary(mod) |>
    group_rows(index = c("Uninteresting" = 4,
                         "Interesting" = 4,
                         "Other" = 7))