Standard deviation of residuals

Very similar to standard deviation of a series - \(S_r = \sqrt{\frac{(r_1)^2 + (r_2)^2 + ... + (r_n)^2}{(n - 1)}}\) - Take the residual of each point on the scatterplot (against the regression line), square it, divide by (1-n), and square root the whole thing - Then, you can take that standard deviation and draw a line on each side of the regression line to show values that are within 1 Standard Deviation of the regression line - https://www.khanacademy.org/math/statistics-probability/describing-relationships-quantitative-data/assessing-the-fit-in-least-squares-regression/v/standard-deviation-of-residuals-or-root-mean-square-error-rmsd?modal=1

!