plotCoeffs: Plot model coefficients with confidence intervals

In modEvA: Model Evaluation and Analysis

Plot model coefficients with confidence intervals

Description

Gets the coefficient estimates of a model with their 95% confidence intervals, and shows them in a point range plot.

Usage

  plotCoeffs(model, labels = NULL, plot = TRUE, ...)

Arguments

model	A model object of class "glm", "lm" or "phylolm".
labels	Optional two-column matrix or data frame, with the first column containing names of variables that appear in 'model' (in no particular order), and the second column containing the corresponding names to use as labels in the plot. Can be useful when the model contains abbreviated variable names, and you want more complete variable names in the plot.
plot	Logical value. If set to FALSE, only the results data frame is produced, and no plot.
...	(If plot=TRUE) additional arguments to pass to lollipop, e.g. horizontal = TRUE.

Details

This function uses summary to get the coefficients (excluding the intercept) and their standard errors from a fitted model object, and it computes the 95% confidence intervals, i.e. each coefficient plus/minus 1.96 times its standard error. By default, it also uses lollipop to produce a point range plot with those results. In the plot, the labels of coefficients with significant p-values (<= 0.05) are displayed in bold.

Note that coefficients are only directly comparable if the variables were standardized or if they vary in the same scale.

Value

A data frame (and a plot).

Author(s)

A. Marcia Barbosa

See Also

varImp, lollipop

Examples

# get example model:

mod <- glm(am ~ mpg + wt + gear + carb, data = as.data.frame(scale(mtcars)))

summary(mod)


# default plot:

plotCoeffs(mod)


# with some plot tweaks:

labels <- data.frame(
  vars = c("gear", "wt", "mpg", "carb"), 
  labs = c("N gears", "Weight", "Miles per gallon", "N carburators")
  )

par(mar = c(3, 10, 2, 1))

plotCoeffs(mod, horiz = TRUE, cex = 2, grid = FALSE, axis.lab = "Coefficients", 
main = "Transmission", labels = labels, col = "purple")

modEvA documentation built on March 20, 2025, 3:01 a.m.