An R Introduction to Statistics

Residual Plot

The residual data of the simple linear regression model is the difference between the observed data of the dependent variable y and the fitted values ŷ.

Residual = y- ˆy


Plot the residual of the simple linear regression model of the data set faithful against the independent variable waiting.


We apply the lm function to a formula that describes the variable eruptions by the variable waiting, and save the linear regression model in a new variable eruption.lm. Then we compute the residual with the resid function.

> eruption.lm = lm(eruptions ~ waiting, data=faithful) 
> eruption.res = resid(eruption.lm)

We now plot the residual against the observed values of the variable waiting.

> plot(faithful$waiting, eruption.res, 
+     ylab="Residuals", xlab="Waiting Time", 
+     main="Old Faithful Eruptions") 
> abline(0, 0)                  # the horizon



Further detail of the resid function can be found in the R documentation.

> help(resid)