6.1 the standard casewise diagnostic plots

6.1.2 mtx algebra

6.1.3 added var plots

6.2 transformations

6.2.1 nonlinearity

6.2.2 logs and percents

6.3 marginal model plots

6.4 multicollinearity

6.4.1 VIFs

6.5 wine critics' ratings

6.6 observational studies and omitted vars

6.6.1 spurious correlations

6.6.2 the math

6.6.3 omitted vars in obs studies