How to add the p-value to the ggplot charts

An R library called ggpval allows us to perform statistical tests by adding the corresponding p-value to the ggplot charts.

How to Install the ggpval library

We can install the ggpval library either from CRAN or from GitHub

# Install `ggpval` from CRAN:
install.packages("ggpval")

# You can install the lastest ggpval from github with:
# install.packages("devtools")
devtools::install_github("s6juncheng/ggpval")

Let’s run a simple example of a t-test by comparing two groups.

library(ggpval)
library(tidyverse)

set.seed(5)

X1<-rnorm(100, 0, 1)
X2<-rnorm(100, 2, 1)

Groups<-rep(c("G1", "G2"), each = 100)
Values<-c(X1,X2)
df<-data.frame(Groups=Groups, Values=Values)


plt <- ggplot(df, aes(Groups, Values)) +
  geom_boxplot() +
  geom_jitter()

add_pval(plt, pairs = list(c(1, 2)))

As we can see, the P-Value was added at the top of the chart (P<2e-16).