Formulas Useful for Linear Regression Analysis and Related Matrix Theory : It's Only Formulas But We Like Them

The Model Matrix.
Fitted Values and Residuals.
Regression Coefficients.
Alternative Estimators.
Decompositions of Sums of Squares.
Partial Correlations.
Distributions.
Testing Hypotheses.
Diagnostics.
BLUE: Some Helpful Identities.
Estimability.
Best Linear Unbiased Estimator.
The Watson Efficiency.
Linear Sufficiency and Admissibility.
Best Linear Unbiased Predictor.
Mixed Model.
Multivariate Linear Model.
Inverse of a Partitioned Matrix.
Generalized Inverses.
Projectors.
Eigenvalues.
Discriminant Analysis.
Factor Analysis.
Canonical Correlations.
Matrix Decompositions.
Principal Component Analysis.
Löwner Ordering.
Rank Rules.
Inequalities.
Kronecker Product.
Matrix Derivatives.