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Quantile/expectile regression, and extreme data analysis

Quantile/expectile regression, and extreme data analysis

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Expectile <strong>regression</strong><br />

Interrelationship between <strong>expectile</strong>s <strong>and</strong> quantiles† I<br />

“Expectiles have properties that are similar to quantiles” (Newey <strong>and</strong><br />

Powell, 1987). The reason is that <strong>expectile</strong>s of a distribution F are<br />

quantiles a distribution G which is related to F (Jones, 1994).<br />

The main details are as follows.<br />

Let<br />

P(s) =<br />

∫ s<br />

−∞<br />

y f (y) dy<br />

ρ [1]<br />

τ (u) = τ − I (u ≤ 0),<br />

ρ [2]<br />

ω (u) = |u|(ω − I (u < 0)).<br />

the (first) partial moment,<br />

© T. W. Yee (University of Auckl<strong>and</strong>) <strong>Quantile</strong>/<strong>expectile</strong> <strong>regression</strong>, <strong>and</strong> <strong>extreme</strong> <strong>data</strong> <strong>analysis</strong> 18 July 2012 @ Cagliari 36/101/

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