Exercise · ZW-ESTIMATOR-010 · ★★★ Advanced

A sample of size \(n=4\) comes from \(\mathrm{Unif}(0,\theta)\) with \(\theta=10\). It is known that \(E[\max X_i]=\tfrac{n}{n+1}\theta\). What is the bias of \(\max X_i\) as an estimator of \(\theta\)?

Choose one option.

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  • D. \(-2\)

Explanation

\(E[\max X_i]=\tfrac45\cdot10=8\), so the bias is \(8-10=-2\): the sample maximum never exceeds \(\theta\), so on average it underestimates it.

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Review the concept: Estimator

An estimator \(\hat\theta\) is a rule \(T\), a function of the random sample \(X_i\), that produces a value used to approximate an unknown population parameter \(\theta\).

\[\hat\theta=T(X_1,\dots,X_n)\]

More practice problems: estimator

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