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Lecture7 Slide - The Department of Statistics and Applied Probability ...

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12<br />

Multivariate nonparametric estimation<br />

• Bias <strong>and</strong> variance functions are<br />

{ 1<br />

b α (x) = µ 2 (K)<br />

2<br />

{∫<br />

v(x) = σ 2 (x)f −1 (x)<br />

∂ 2 m<br />

∂ 2 (x) + ∂m (x) ∂f (x) f −1 (x)<br />

x α ∂x α ∂x α<br />

} d<br />

K 2 (u) du<br />

• <strong>The</strong> local linear estimator (to be discussed next) has limiting<br />

distribution <strong>of</strong> the same form, but with<br />

b α (x) = µ 2 (K) 1 2<br />

∂ 2 m<br />

∂ 2 x α<br />

(x)<br />

• <strong>The</strong> local linear weighted least squares problem is<br />

n∑ {<br />

2<br />

{ ˆm (x) , ∇m (x)} = arg min Y i − a − (X i − x) b} T wi (x)<br />

a,b<br />

i=1<br />

}<br />

ST5207 Nonparametric Regression, 10th March 2005

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