For a statistic to be a good estimator of a parameter, two properties it must satisfy are unbiasedness and minimum variance. Consider a sample of three observations X₁, X₂, X, where X, ~ Exp (0). That is, a sample of size 3 is taken from a population following the exponential distribution with density function given by 3 f(x)= 0, -e-%¸ if x > 0 Otherwise. Five possible estimators of are Ô‚ = X₁, ô₂ = ¹/(X₁ + X₂), Ô‚ = — (X₁ + 2X₂), Ô₁ = X, and ô₂ = -—(X₁ + X). 2 [Hint: Use the fact that for variable X we have E(X)= 0 and E(X²)=20² and Var(X) = 0²2. (a) Show that the five estimators given above are unbiased for 0. (b) Find the variances of each of the five estimators. (c) Which estimator will you choose for 0. Why?

Glencoe Algebra 1, Student Edition, 9780079039897, 0079039898, 2018
18th Edition
ISBN:9780079039897
Author:Carter
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Chapter10: Statistics
Section10.5: Comparing Sets Of Data
Problem 13PPS
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For a statistic to be a good estimator of a parameter, two properties it must satisfy
are unbiasedness and minimum variance. Consider a sample of three observations
X₁, X₂, X, where X, ~ Exp (0). That is, a sample of size 3 is taken from a population
2 3
following the exponential distribution with density function given by
f(x) =
1e % if x > 0
0, Otherwise.
Five possible estimators of are â‚ =X₁, Ô₂ = ¹/(X₁ + X₂), Ô‚ = =— (X₁ + 2X₂),
Ô¸ = X, and Ô¸ = ¹⁄ (X₂ + X).
2
[Hint: Use the fact that for variable X we have E(X)= 0 and E(X²)=20² and
Var(X) = 0².
(a) Show that the five estimators given above are unbiased for 0.
(b) Find the variances of each of the five estimators.
(c) Which estimator will you choose for 0. Why?
Transcribed Image Text:For a statistic to be a good estimator of a parameter, two properties it must satisfy are unbiasedness and minimum variance. Consider a sample of three observations X₁, X₂, X, where X, ~ Exp (0). That is, a sample of size 3 is taken from a population 2 3 following the exponential distribution with density function given by f(x) = 1e % if x > 0 0, Otherwise. Five possible estimators of are â‚ =X₁, Ô₂ = ¹/(X₁ + X₂), Ô‚ = =— (X₁ + 2X₂), Ô¸ = X, and Ô¸ = ¹⁄ (X₂ + X). 2 [Hint: Use the fact that for variable X we have E(X)= 0 and E(X²)=20² and Var(X) = 0². (a) Show that the five estimators given above are unbiased for 0. (b) Find the variances of each of the five estimators. (c) Which estimator will you choose for 0. Why?
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