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Asymptotic Methods in Statistical Inference - Statistics Centre

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191<br />

• The MLE is not the only efficient estimator, for<br />

<strong>in</strong>stance ‘+ <br />

³<br />

<br />

−12´’ isalsoefficient. A<br />

less trivial example is if 1 ∼ ³ = 2´<br />

for a known (= 1). To obta<strong>in</strong> the MLE ˆ<br />

it is convenient to first obta<strong>in</strong> ˆ, where =1.<br />

We def<strong>in</strong>e 2 = P 2 and calculate<br />

(<br />

() ∝ − exp − 1 X ( − ) 2 )<br />

2 2 ½<br />

= exp − 1 X<br />

( − ) 2¾ <br />

2<br />

() = + log − 1 2 2 2 + ¯<br />

0 () = <br />

(<br />

1<br />

− 2 + ¯<br />

and then<br />

)<br />

<br />

ˆ =<br />

r ³<br />

¯ + ¯´2 +42<br />

<br />

2 2<br />

ˆ = 1ˆ = s µ<br />

2 ¯ 2<br />

+ 2 − 2 ¯

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