Consider the Following Symmetric and Idempotent Matrix A: a =

question 50

Essay

Consider the following symmetric and idempotent Matrix A: A = I - ιι' and ι = a.Show that by postmultiplying this matrix by the vector Y (the LHS variable of the OLS regression),you convert all observations of Y in deviations from the mean.
b.Derive the expression Y'AY.What is the order of this expression? Under what other name have you encountered this expression before?

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Definitions:

Defensive Medicine

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Medical Lawsuits

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Managed-Care Systems

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