Assessing the fit in least-squares regression

Let's learn how to measure how well a linear model actually fits the relationship in a scatterplot using residual plots and r-squared. We'll also look at how outliers can be influential points in least-squares regression.

Residual plots

Residual plots

R-squared or coefficient of determination

Standard deviation of residuals or Root-mean-square error (RMSD)

Interpreting computer regression data

Impact of removing outliers on regression lines

Effects of influential points