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Often when we perform simple linear regression, weâ€™re interested in creating a scatterplot to visualize the various combinations of x and y values.

Fortunately, R makes it easy to create scatterplots using theÂ **plot()Â **function. For example:

#create some fake data data #create scatterplot of data plot(data$x, data$y)

Itâ€™s also easy to add a regression line to the scatterplot using theÂ **abline()Â **function. For example:

#fit a simple linear regression model model #add the fitted regression line to the scatterplot abline(model)

We can also add confidence interval lines to the plot by using theÂ **predict()Â **function. For example:

#define range of x values newx = seq(min(data$x),max(data$x),by = 1) #find 95% confidence interval for the range of x values conf_interval #create scatterplot of values with regression line plot(data$x, data$y) abline(model) #add dashed lines (lty=2) for the 95% confidence interval lines(newx, conf_interval[,2], col="blue", lty=2) lines(newx, conf_interval[,3], col="blue", lty=2)

Or we could instead add prediction interval lines to the plot by specifying the interval type withinÂ the **predict()** function. For example:

#define range of x values newx = seq(min(data$x),max(data$x),by = 1) #find 95% prediction interval for the range of x values pred_interval interval="prediction", level = 0.95) #create scatterplot of values with regression line plot(data$x, data$y) abline(model) #add dashed lines (lty=2) for the 95% confidence interval lines(newx, pred_interval[,2], col="red", lty=2) lines(newx, pred_interval[,3], col="red", lty=2)

Lastly, we can make the plot more aesthetically pleasing by adding a title, changing the axes names, and changing the shape of the individual points in the plot.

plot(data$x, data$y, main = "Scatterplot of x vs. y", #add title pch=16, #specify points to be filled in xlab='x', #change x-axis name ylab='y') #change y-axis name abline(model, col='steelblue') #specify color of regression line

**Additional Resources**

How to Label Points on a Scatterplot in R

How to Use the Jitter Function in R for Scatterplots