Section 9c

9.4 Effect of Outliers, 9.5 Robustness of the F-Test to Nonnormality: 9.5.1 Effect of the Regressor Variables, 9.5.2 Quadratically Balanced F-Tests

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Problem 9c.1

Fill in the details of the proof of Theorem 9.2.

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Problem 9c.2

Show that the theory of Section 9.5.2 can also be applied to the case H:Aβ=cH: \mathbf{A} \mathbf{\beta } = \mathbf{c}, where c≠0\mathrm{c} \neq \mathbf{0}.

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Problem 9c.3

Consider the full-rank regression model

Yi=β0+β1xi1+⋯+βp−1xi,p−1+εi(i=1,2,…,n) Y_{i} = \beta _{0}+\beta _{1} x_{i 1}+\cdots +\beta _{p-1} x_{i, p-1}+\varepsilon _{i} \quad (i = 1,2, \ldots , n)

where the εi\varepsilon_{i} are independently and identically distributed as N(0,σ2)N\left(0, \sigma^{2}\right), and suppose that we wish to test H:β1=β2=⋯=βp−1=0H: \beta_{1} = \beta_{2} = \cdots = \beta_{p-1} = 0.

Assuming that HH is true, find an approximate expression for E[Z]\mathbb {E}\left[Z\right], where Z=12log⁡FZ = \frac{1}{2} \log F, in terms of the diagonal elements of X(XTX)−1XT\mathbf{X}\left(\mathbf{X}^{T} \mathbf{X}\right)^{-1} \mathbf{X}^{T}.

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