Parameter regions for quarterly data
Fig. 10.3. Light-shaded region: the forecastable region of α; and β; for model ETS(A,Ad,A) with m = 4. Dark-shaded region: the usual region where 0 < α; < 1 − γ; and 0 < β; < α. The right column shows the region for model ETS(A,A,A) (when φ = 1).
160 10 Some Properties of Linear Models
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And
where 1k denotes a k-vector of ones. The characteristic equation for D is given by
