*90*

Often you may want to add a regression equation to a plot in R as follows:

Fortunately this is fairly easy to do using functions from the **ggplot2** and** ggpubr** packages.

This tutorial provides a step-by-step example of how to use functions from these packages to add a regression equation to a plot in R.

**Step 1: Create the Data**

First, letâ€™s create some fake data to work with:

#make this example reproducible set.seed(1) #create data frame df frame(x = c(1:100)) df$y #view head of data frame head(df) x y 1 1 -8.529076 2 2 11.672866 3 3 -4.712572 4 4 47.905616 5 5 26.590155 6 6 7.590632

**Step 2: Create the Plot with Regression Equation**

Next, weâ€™ll use the following syntax to create a scatterplot with a fitted regression line and equation:

#load necessary libraries library(ggplot2) library(ggpubr) #create plot with regression line and regression equation ggplot(data=df, aes(x=x, y=y)) + geom_smooth(method="lm") + geom_point() + stat_regline_equation(label.x=30, label.y=310)

This tells us that the fitted regression equation is:

**y = 2.6 + 4*(x)**

Note thatÂ **label.x** andÂ **label.y** specify the (x,y) coordinates for the regression equation to be displayed.

**Step 3: Add R-Squared to the Plot (Optional)**

You can also add the R-squared value of the regression model if youâ€™d like using the following syntax:

#load necessary libraries library(ggplot2) library(ggpubr) #create plot with regression line, regression equation, and R-squared ggplot(data=df, aes(x=x, y=y)) + geom_smooth(method="lm") + geom_point() + stat_regline_equation(label.x=30, label.y=310) + Â Â Â Â stat_cor(aes(label=..rr.label..), label.x=30, label.y=290)

The R-squared for this model turns out to beÂ **0.98**.

You can find more R tutorials on this page.