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Slika - Shrani.si

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A. Juriˇ<strong>si</strong>ć in V. Batagelj: Verjetnostni račun in statistika 353<br />

✬<br />

✫<br />

Učinkovitost cenilke<br />

Naj bo C0 najučinkovitejˇsa cenilka parametra ζ in C kaka druga nepristranska<br />

cenilka. Tedaj je učinkovitost cenilke C določena s predpisom<br />

e(C) = DC0<br />

DC<br />

Učinkovitost najučinkovitejˇse cenilke je e(C0) = 1.<br />

Če najučinkovitejˇsa cenilka ne obstaja, vzamemo za vrednost DC0 desno<br />

stran v Rao-Cramérjevi oceni.<br />

Primer: Naj bo X : N(µ, σ). Pri velikih n-jih je vzorčna mediana ˜ X –<br />

ocena za µ, porazdeljena pribliˇzno po N(µ, σ π<br />

2n ). Torej je<br />

e( ˜ X) = DX<br />

D ˜ X =<br />

σ 2<br />

n<br />

πσ 2<br />

2n<br />

= 2<br />

π<br />

≈ 0.64<br />

Univerza v Ljubljani ▲<br />

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● ❙ ▲<br />

▲<br />

☛ ✖<br />

▲<br />

✩<br />

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