Learn essential techniques for improving linear model fit through diagnostic analysis. Explore Ordinary Least Squares (OLS) regression on Anscombe data, conduct residual analysis, and interpret various residual plots. Master the use of Normal Q-Q plots to check for error normality, detect non-uniform error variance, and identify outliers in datasets. Apply these skills to real-world examples, including US Bonds data, and understand how to refine models by removing outliers for more accurate results.