Institute of Mathematics, University of Rzeszów, Rejtana 16 A, 35-959 Rzeszów, Poland
Copyright © 2010 Czesław Stępniak. This is an open access article distributed under the
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Gauss-Markov theorem reduces linear unbiased estimation to the Least Squares Solution of inconsistent linear equations while the normal equations reduce the second one to the usual solution of consistent linear equations.
It is rather surprising that the second algebraic result is usually derived in a differential way. To avoid this dissonance, we state and use an auxiliary result on equivalence of two systems of linear equations. This places us in a convenient position to attack on the main problems in the Gauss-Markov model in an easy way.