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Asymptotic Methods in Statistical Inference - Statistics Centre

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64<br />

(i) the t-test ( = ¯() = ), for which<br />

( ) → Φ(∆ − )with =1,<br />

(ii) the sign test, with =2(0). The ARE of<br />

the sign test to the t-test is ( =1)<br />

à ! 2 <br />

= =(2(0)) 2 <br />

<br />

This can be arbitrarily large or small; for ∼<br />

(0 2 )itis =2 ≈ 637 . For the Laplace<br />

(() =5exp(−||), 2 =2)itis2.<br />

(iii) An alternative procedure is the one-sample<br />

Wilcoxon test: Rank the | | and sum the ranks<br />

(rather than merely the signs) of the positive .<br />

Let be this sum and def<strong>in</strong>e = ³ <br />

2<br />

´; large<br />

values support . For alternatives = ∆ √ <br />

it can be shown (and will be <strong>in</strong> Lecture 16) that<br />

√ ( − ( ))<br />

q<br />

13<br />

<br />

→ (0 1)<br />

where () = ( 1 + 2 0) and 1 2<br />

are distributed <strong>in</strong>dependently, and symmetrically<br />

around , withd.f. ( ≤ ) = ( − ). Thus<br />

(0) = 12 —def<strong>in</strong><strong>in</strong>g the rejection region — and

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